Image credit: © Jeff Curry-USA TODAY Sports

Hello everyone, and a very pleasant day to you, wherever you may be. Today we’ll be presenting part 3 of our ongoing series annotating and explaining the Official Baseball Rules. If you haven’t already read parts 1 and 2, you’ll want to begin there, as they cover the objectives of the game and the playing field, respectively. Today we will be looking at EQUIPMENT AND UNIFORMS. It is on the long side, as the rules will begin to become from here on out, so we appreciate your patience and understanding.


Section 3 of the official rules is broken down into the following subsections: the ball, the bat, player uniforms, catcher’s mitt, first baseman’s glove, fielding gloves, pitcher’s glove, helmets, undue commercialization and equipment on the field. As you can tell this is a wide-ranging section, so let’s get started.

3.01 The Ball

The ball shall be a sphere formed by yarn wound around a small core of cork, rubber or similar material, covered with two strips of white horsehide or cowhide, tightly stitched together. It shall weigh not less than five nor more than 51⁄4 ounces avoirdupois and measure not less than nine nor more than 91⁄4 inches in circumference.

No player shall intentionally discolor or damage the ball by rubbing it with soil, rosin, paraffin, licorice, sand-paper, emery- paper or other foreign substance.

PENALTY:The umpire shall demand the ball and remove the offender from the game. In addition, the offender shall be suspended automatically for 10 games. For rules in regard to a pitcher defacing the ball, see Rules 6.02(c)(2) through (6).

Rule 3.01 Comment: Should a ball come partially apart in a game, it is in play until the play is completed.

First, right off the bat (ha), it is a sphere formed by wound yarn—but what kind of yarn? Wool? Cotton? Alpaca? As it turns out it’s about 316 yards of wool, but seemingly more by tradition than adherence to the rule. But pay that no nevermind, because you are free to wrap the yarn around cork, rubber or any similar material. Of course cork and rubber aren’t particularly similar—rubber weighs about 1.2 grams per cubic centimeter on average and cork is more in the vicinity of 0.24, fully 1/5th the weight. They have differing compressive properties, as well.

The vagueness with which the materials are described is reflected in the variation in acceptable sizes and weights, as well. A weight range of ¼ ounce and a size range of ¼ inch may sound insignificant, and to some extent it is—but as we have already mentioned and you may have noticed on your own, baseball is a game of milliseconds and inches. A piece of chewing gum weighs about 0.05 ounces, and I’m made to understand slapping a piece on the leather can make a difference in how the ball travels.

The second paragraph is so broad and so regularly violated as to be entirely useless. No player can intentionally discolor or damage the ball by, essentially, rubbing it with anything that could be on their hands. So they can’t really rub the ball, or if they do so they have to ensure they don’t get it dirty or scuffed up. There is a pair of rosin bags just behind the mound, the pitcher in all likelihood is about 10 seconds removed from having handled them. They will, without fail, do that rubbing thing they do while staring down at the catcher and preparing to receive the sign. This rule is clearly aimed at arresting large-scale scuffing for purposes of increasing grip on the ball, but as with so many rules involving pitcher behavior, it fails the “comprehensible” test: you don’t come away feeling like you, as a pitcher, are clear on what is and is not acceptable behavior. Or perhaps more accurately, you would come away with a misguided sense of the strictures of behavior vis a vis the ball as against what you’d actually see if you observed a game.

3.02 The Bat

(a) The bat shall be a smooth, round stick not more than 2.61 inches in diameter at the thickest part and not more than 42 inches in length. The bat shall be one piece of solid wood.

NOTE: No laminated or experimental bats shall be used in a professional game (either championship season or exhibition games) until the manufacturer has secured approval from the Rules Committee of his design and methods of manufacture.

(b) Cupped Bats. An indentation in the end of the bat up to 11⁄4 inches in depth is permitted and may be no wider than two inches and no less than one inch in diameter. The indentation must be curved with no foreign substance added.

(c) The bat handle, for not more than 18 inches from its end, may be covered or treated with any material or substance to improve the grip. Any such material or substance that extends past the 18-inch limitation shall cause the bat to be removed from the game.

NOTE: If the umpire discovers that the bat does not conform to (c) above until a time during or after which the bat has been used in play, it shall not be grounds for declaring the batter out, or ejected from the game.

Rule 3.02(c) Comment: If pine tar extends past the 18-inch limitation, then the umpire, on his own initiative or if alerted by the opposing team, shall order the batter to use a different bat. The batter may use the bat later in the game only if the excess substance is removed. If no objections are raised prior to a bat’s use, then a violation of Rule 3.02 (c) on that play does not nullify any action or play on the field.

(d) No colored bat may be used in a professional game unless approved by the Rules Committee.

The bat description is every bit as ambiguous as the ball: it is a solid wood stick, less than 42 inches in length, and not more than 2.61 inches in diameter. Mini bats, cut down broom handles, and round table legs presumably would all fit the bill. There are no species limitations and both the length and thickness constraints are only on the upper end. Perhaps most interestingly, it doesn’t appear that the bat needs to be straight. One wonders what kind of opposite-field action a hitter could achieve with a curved bat. Maybe the shift doesn’t need to be done away with if sickle-shaped bats start popping up.

Some of the wiggle room is done away by the note on 3.02(a)—presumably any deviation from the traditional bat would qualify as an “experimental bat” and would be subject to Rules Committee approval. This is a good catchall provision to prevent shenanigans, but if this a piece of legislation one would want to see more clarity in the text itself, rather than simply punting all questions to the committee. If some dimensions are outlined, then sufficient dimensions should be outlined to determine a piece of equipment’s conformance to the rules simply by reading them.

Fans of baseball should be able to identify the play that eventually gave rise to 3.02(c) and the accompanying note. After George Brett’s 1983 “Pine Tar Incident,” the then-American League President upheld a protest by the Kansas City Royals and restored his home run in light of the “spirit” of the rule not being to rob players of hits post-hoc for unintentionally running slightly afoul of the restriction. It took until 2010 for the rules to be amended to reflect that interpretation and formally restrict an objection made after a play from taking away a hit.

3.03 Player Uniforms

(a) All players on a team shall wear uniforms identical in color, trim and style, and all players’ uniforms shall include minimal six-inch numbers on their backs.
(b) Any part of an undershirt exposed to view shall be of a uniform solid color for all players on a team. Any player other than the pitcher may have numbers, and /or letters, insignia attached to the sleeve of the undershirt.
(c) No player whose uniform does not conform to that of his teammates shall be permitted to participate in a game.
(d) A league may provide that each team shall wear a distinctive uniform at all times, or that each team shall have two sets of uniforms, white for home games and a different color for road games.
(e) Sleeve lengths may vary for individual players,but the sleeves of each individual player shall be approximately the same length; no player shall wear ragged, frayed or slit sleeves; and no pitcher shall wear sleeves that are white, gray, nor, in the judgment of an umpire, distracting in any manner.
(f) No player shall attach to his uniform tape or other material of different color from his uniform.
(g) No part of the uniform shall include a pattern that imitates or suggests the shape of a baseball.
(h) Glass buttons and polished metal shall not be used on a uniform.
(i) No player shall attach anything to the heel or toe of his shoe other than the ordinary shoe plate or toe plate. Shoes with pointed spikes similar to golf or track shoes shall not be worn.
(j) No part of the uniform shall include patches or designs relating to commercial advertisements.
(k) A league may provide that the uniforms of its member teams include the names of its players on their backs. Any name other than the last name of the player must be approved by the Office of the Commissioner. If adopted, all uniforms for a team must have the names of its players.

As an example of statutory drafting, this section is pretty solid: it describes in detail a set of rules that, if you imagined a player uniform that meets the requirements of said rules, you’d get pretty close to what you see on the field today. A few points do stick out as worthy of noting, however.

First, player numbers on the back—we don’t know of any team uniform that conforms to the “minimal six-inch numbers” if that is read to mean the numbers should be a) minimal and b) six-inch in size. If the intent was instead to set six-inches as the minimum size, then this section falls down a bit in terms of clarity. It could be rewritten to read: “All players on a team shall wear uniforms identical in color, trim, and style, and all players’ uniforms shall include numbers of at least six-inches in vertical measurement on their backs.”

Second, (g) precludes patterns that imitate or suggest the shape of a baseball. The Cincinnati Reds and San Francisco Giants just straight up have baseballs on their sleeves. The former is Mr. Red, an anthropomorphized baseball that kind of looks like what the W.B. Mason guy would look like in a Pixar movie where everyone had a baseball head—but he is at least suggestive of a baseball shape.

And finally, (j) and the Nike swoosh. Obviously, MLB had a billion reasons to permit this exception and it wasn’t done without fans taking notice. There is an argument to be made on either side of commercialism that adding the logo to the front of the uniform does or does not violate some sacred tradition. You can even make a purely aesthetic argument—it does ruin the symmetry of some uniforms and how it lines up with the team chest patch is often kind of offset and frustrating for the ordered among us. But time marches on and commercialism has always been a part of baseball.

What you can’t defend, however, is leaving the rule unamended. Perhaps no other section of the rules that we have covered so far is so egregiously and systematically broken. All 30 teams’ uniforms carry the swoosh and, granted, New Era logos on the caps and myriad other smaller logos that could be said to be on the broader “uniform.” If the rule is no longer applicable, simply amend the rule. Perhaps doing so would codify the break with tradition in a way that is less palatable, and it’s easier to view the Nike swoosh as a special case—but does anyone believe that when Nike’s ten year contract comes up the spot will thereafter go unoccupied? If the Pine Tar Incident took 27 years to get a rule amendment, perhaps we can look forward to an update here sometime prior to the 2050 season.

3.04 Catcher’s Mitt

The catcher may wear a leather mitt not more than thirty-eight inches in circumference, nor more than fifteen and one-half inches from top to bottom. Such limits shall include all lacing and any leather band or facing attached to the outer edge of the mitt. The space between the thumb section and the finger section of the mitt shall not exceed six inches at the top of the mitt and four inches at the base of the thumb crotch. The web shall measure not more than seven inches across the top or more than six inches from its top to the base of the thumb crotch. The web may be either a lacing, lacing through leather tunnels, or a center piece of leather which may be an extension of the palm, connected to the mitt with lacing and constructed so that it will not exceed any of the above mentioned measurements.

Remember our discussion of mandatory versus discretionary language in drafting? In the first sentence of this section we have a discretionary statement—the catcher may wear a mitt. First, this suggests that a catcher need not wear a mitt if said catcher doesn’t want to. I’d like to see this be attempted at least once. Second, the language is a bit unclear—combining both the discretionary mitt-or-no-mitt statement with the language placing limits on the mitt’s size creates an ambiguity. Common sense tells us that they intended to say the catcher may wear a mitt and if the catcher chooses to, the mitt must conform to these requirements. However, another arguably equally plausible way to interpret the line is that a catcher may wear a mitt of those dimensions, or no mitt, or another mitt of any dimensions they so choose.

This second somewhat-ridiculous interpretation that would allow for novelty 8’ mitts is lent more credence with the second sentence, where “shall” (mandatory) language is used to connect the lacing limits to the overall dimension limits—but the latter is still subject to the discretionary language so the result remains ambiguous.

The fix here would be to simply break the first sentence into two separate statements: “The catcher may wear a leather mitt. Said leather mitt shall not be more than thirty-eight inches in circumference, nor more than fifteen and one-half inches from top to bottom.”

3.05 First Baseman’s Glove

The first baseman may wear a leather glove or mitt not more than thirteen inches long from top to bottom and not more than eight inches wide across the palm, measured from the base of the thumb crotch to the outer edge of the mitt. The space between the thumb section and the finger section of the mitt shall not exceed four inches at the top of the mitt and three and one-half inches at the base of the thumb crotch. The mitt shall be constructed so that this space is permanently fixed and cannot be enlarged, extended, widened, or deepened by the use of any materials or process whatsoever. The web of the mitt shall measure not more than five inches from its top to the base of the thumb crotch. The web may be either a lacing, lacing through leather tunnels, or a center piece of leather which may be an extension of the palm connected to the mitt with lacing and constructed so that it will not exceed the above mentioned measurements. The webbing shall not be constructed of wound or wrapped lacing or deepened to make a net type of trap. The glove may be of any weight.

As with the catcher’s mitt, the material is limited to “leather”—which could probably be firmed up a bit. Cow hide? Horse hide? Top grain? Full grain? The glove being of any weight coupled with the broad language of “leather” creates an opportunity for some boundary-pushing super lightweight leather composites to make an appearance.

3.06 Fielding Gloves

Each fielder, other than the catcher, may use or wear a leather glove. The measurements covering size of glove shall be made by measuring front side or ball receiving side of glove. The tool or measuring tape shall be placed to contact the surface or feature of item being measured and follow all contours in the process. The glove shall not measure more than 13 inches from the tip of any one of the 4 fingers, through the ball pocket to the bottom edge or heel of glove. The glove shall not measure more than 73⁄4 inches wide, measured from the inside seam at base of first finger, along base of other fingers, to the outside edge of little finger edge of glove. The space or area between the thumb and first finger, called crotch, may be filled with leather webbing or back stop. The webbing may be constructed of two plies of standard leather to close the crotch area entirely, or it may be constructed of a series of tunnels made of leather, or a series of panels of leather, or of lacing leather thongs. The webbing may not be constructed of wound or wrapped lacing to make a net type of trap. When webbing is made to cover entire crotch area, the webbing can be constructed so as to be flexible. When constructed of a series of sections, they must be joined together. These sections may not be so constructed to allow depression to be developed by curvatures in the section sides. The webbing shall be made to control the size of the crotch opening. The crotch opening shall measure not more than 41⁄2 inches at the top, not more than 5 3⁄4 inches deep, and shall be 3 1⁄2 inches wide at its bottom. The opening of the crotch shall not be more than 4 1⁄2 inches at any point below its top. The webbing shall be secured at each side, and at top and bottom of crotch. The attachment is to be made with leather lacing, these connections to be secured. If they stretch or become loose, they shall be adjusted to their proper condition. The glove can be of any weight. See Appendix 4 for diagram of glove dimensions.

The first line sets up the catcher as a “fielder”—which may have implications later. Interestingly, for the fielding gloves the rules lay out how to measure the gloves—something we don’t see for the catcher’s mitt or first baseman. However, it might be that in the case of the first baseman section 3.05 is intended to be read in conjunction with 3.06 as presumably the first baseman is a fielder, but this is not at all clear. Taken at face value one could reasonably assume that the rules are classifying fielders as players other than the first baseman and the pitcher, which can’t possibly be the intent.

Additionally, the rules permit each fielder to “use or wear” a leather glove. Wear is self explanatory, though you might clarify that the fielder should wear it on their hand. Use, however, is ambiguous. Presumably it is intended to permit something like a second baseman tossing a ball inside of their removed glove to first base to record an out, or a glove that is taken off of a fielder’s hand by a hard hit ball not suddenly becoming a little rule-violating time bomb waiting for someone to touch it. That all makes sense, but is an awful lot for “use” to be lifting and requires substantial expansion in interpretation. The fix would be to rewrite this section to enumerate fielders and set out what one can do with one’s leather glove.

3.07 Pitcher’s Glove

(a) The pitcher’s glove may not, exclusive of piping, be white, gray, nor, in the judgment of an umpire, distracting in any manner. No fielder, regardless of position, may use a fielding glove that falls within a PANTONE® color set lighter than the current 14-series.

(b) No pitcher shall attach to his glove any foreign material of a color different from the glove.

(c) The umpire-in-chief shall cause a glove that violates Rules 3.07(a) or (b) to be removed from the game, either on his own initiative, at the recommendation of another umpire or upon complaint of the opposing manager that the umpire-in-chief agrees has merit.

This is the first rule we have seen that empowers the opposing manager to challenge the propriety of an aspect of gameplay—here, the opposing team pitcher’s glove. The presumption is, then, that an opposing manager cannot challenge another piece of equipment, which raises some questions. It makes some sense that a distracting pitcher’s glove would be the most impactful on the opposing team. One imagines a glove festooned with holiday tinsel would make picking up the ball somewhat more difficult for a hitter—but what about another fielder’s glove that lends the fielder some competitive advantage. A foam-finger sized second baseman’s glove, for example. It is incumbent upon the umpire to spot and remove said glove.

Specifically delineating who can make a complaint about the pitcher’s glove here, and not in the other sections covering the wider uniform, creates an ambiguity. Either the statement here is superfluous, or opposing managers specifically cannot complain about other parts of the uniform. If the latter, the question is raised as to what is to be done if a manager does complain about, for instance, a first baseman’s dayglo-orange glove. If the umpire-in-chief agrees that the complaint has merit, can the glove be removed from the game? Or has the fact of the manager being the one to draw the umpire’s attention to it mean it must be permitted to stay.

3.08 Helmets

A Professional League shall adopt the following rule pertaining to the use of helmets:

(a) All players shall use some type of protective helmet while at bat and while running the bases.
(b)  All players in the Minor Leagues shall wear a double ear-flap helmet while at bat.
(c) All Major League players must wear a single ear-flap helmet (or at the player’s option, a double ear-flap helmet).
(d) All catchers shall wear a catcher’s protective helmet and face mask while receiving a pitch.
(e) All base coaches shall wear a protective helmet while performing their duties.
(f) All bat/ball boys or girls shall wear a double ear-flap protective helmet while performing their duties.

Rule 3.08 Comment: If the umpire observes any violation of these rules, he shall direct the violation to be corrected. If the violation is not corrected within a reasonable time, in the umpire’s judgment, the umpire shall eject the offender from the game, and disciplinary action, as appropriate, will be recommended.

Helmet rules are interesting because whether they are for bicycles, motorcycles, or apparently baseball—they always have to be made mandatory (“shall”). You would think that players wouldn’t need to be made to wear helmets, what with the importance of the head and all, but here we are.

Section (c) is very strangely worded. All Major League players have to wear a single-flap helmet, or at their discretion a double flap helmet. The way to convey this is “All Major League players must wear a single or double-flap helmet;” joining a mandatory statement with a discretionary one automatically weakens the mandatory statement.

Sometimes in these rules you can see the shadow of the story behind the addition to the rule. While we can find no record of the tale behind the Rule 3.08 comment, the second sentence is telling. The addition of “within a reasonable time” suggests a batter coming to the plate with some kind of non compliant helmet, being told of its non compliant status, and either returning to the dugout and rummaging around for a long time looking for a better helmet, or continually returning with non compliant helmets. In my mind they’re hard hats, Roman centurion helmets, childrens’ bicycle helmets, etc. This sent the committee scrambling to make an addition, and Rule 3.08’s comment was the result.

3.09 Undue Commercialization

Playing equipment including but not limited to the bases, pitcher’s plate, baseball, bats, uniforms, catcher’s mitts, first baseman’s gloves, infielders’ and outfielders’ gloves and protective helmets, as detailed in the provisions of this rule, shall not contain any undue commercialization of the product. Designations by the manufacturer on any such equipment must be in good taste as to the size and content of the manufacturer’s logo or the brand name of the item. The provisions of this Rule 3.09 shall apply to professional leagues only.

NOTE: Manufacturers who plan innovative changes in baseball equipment for professional baseball leagues should submit same to the Official Playing Rules Committee prior to production.

This section is pretty well drafted and the only note is that it proves that the rules committee can enumerate what it means when it wants to—they didn’t simply refer to “playing equipment” but they instead gave a non-exhaustive list. Whatever team worked on this section could be unleashed on the above and flesh out what exactly does and does not constitute a “fielder.”

3.10 Equipment on the Field

(a) Members of the offensive team shall carry all gloves and other equipment off the field and to the dugout while their team is at bat. No equipment shall be left lying on the field, either in fair or foul territory.
(b) The use of any markers on the field that create a tangible reference system on the field is prohibited.

Another rule that tells us a lot without telling us much. As it turns out, for this one we have a date for when the rule was changed—prior to this addition in November of 1953, players would leave their gloves laying on the field while at bat and the opposing fielders would simply play around them. If you combine this practice with some of the ambiguities outlined above in terms of glove dimensions, prior to 1953 perhaps players could have left enormous leather obstacles littering the field.


Section 3 of the rules, outlining acceptable uniforms and equipment, has quite a few shortcomings. There is inconsistent drafting throughout, and it creates ambiguities that make some sections, in the absence of knowledge about common practice, completely unhelpful. Additionally, there are outdated limitations on things like commercialization that have gone unamended as the interaction between baseball and business has evolved. This section would be a complete rewrite and reorganization.

This is the third part of a 10-part series breaking down the Official Baseball Rules. Coming up in part 4 we will be talking about GAME PRELIMINARIES.


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3.03 (c) -- I once saw a team (Washington? Arizona?) who had alternate jerseys that differed only in the team city/name text on the front. One player came out wearing the wrong one (how?) and was sent back to the clubhouse to change. On the other hand, I have seen pictures of a Washington call-up whose jersey was put together too quickly and read "Natinals" (sic) on the front, and I believe he was allowed to play.
Matthew Gold
Mike Ford of the Angels was wearing the wrong cap Wednesday night. At least it didn't match the rest of his teammates.
Lou Trivino warmed up with Jameson Taillon's jersey -- he was in the bullpen but the bullpen in Oakland is practically on the field. Does that count?
Adam Dunn and Ryan Zimmerman had to wear the Natinals misprints. Turns out this wasn't the only such incident, despite how bush-league/"Major League" it seems: