Any attempt at compiling a list of the game’s top prospects is a dicey proposition at best, but there are several key indicators that give a good sense of whether a prospect will turn into a star, fade into Joe Charboneau-like obscurity, or fall somewhere in between. It’s an inexact science, but with improved access to information such as park factors, GB/FB ratios and splits, as well as the use of metrics like isolated power and systems like PECOTA, we’re seeing more and more tools that can help prospect mavens in their attempt to compile a list that they won’t be embarrassed by in five years.

For example, BP’s Top 50 from 2005, while not without flaws, was better than most. Sure there were pitchers ranked highly (Richie Gardner and Adam Miller) who succumbed to arm injuries. We had thought that Willy Aybar (#34) would develop some power by now and that Edwin Jackson (#45) would improve from his sub-par 2004. Despite those missteps, Baseball Prospectus is proud of the work that went into that list as well as the 2006 version.

With a verifiable cornucopia of prospect lists out in cyberspace, there of course exists a vast array of philosophies governing the compilation of these lists. The king of prospect sites, Baseball America, ranks prospects based on scouting reports, tools, upside, age vs. level of competition and performance. Other sites lean heavily on a player’s walk rate. Take, for example, the case of second baseman Travis Denker, in the Dodgers’ system. After Denker hit .310/.417/.556 in Low A as a 20-year-old, many sites had him among their top 50 and, in one case, much higher. With a BB/PA rate of .147, Denker has exhibited unusual plate discipline for a young prospect. However, what these lofty rankings ignored were his stone hands, iron glove, .155 EqA upon his promotion to High-A that year, and his PECOTA projections. When different ranking systems rate some pieces of the puzzle higher than other systems, wildly differing outcomes will result.

This year, the BP Top 50 was compiled by resident prospect gurus Dayn Perry and Rany Jazayerli. When compiling the list, a host of factors are taken into account. In order to shed some light on how the list was assembled, this piece will outline those factors, and provide a few illustrations from this year’s top 50 list. While in some cases, the rankings are to some extent subjective (Alex Gordon and Justin Upton for instance), several key indicators shed light on players that are underrated on the current prospect scene (Chris Snelling – #40, Rich Hill – #47, and Josh Willingham – #48) as well as overrated (Chuck James, to name one).

Hitting prospects:


  • Contact rate: Being able to put the ball in play and avoid Dunnesque strikeout rates bodes well for a prospect’s future. Simply put, the more often the ball is put in play, the more likely it is that a positive outcome will result. Adam Dunn has a career contact rate of just south of 68%, but when he does connect, good things tend to happen. Normally, PECOTA does not look kindly on a contact rate much lower than 75%.

    Joel Guzman‘s rate of 71% in 2005 likely knocked him down a couple of rungs on the Top 50. BP though still has Guzman rated #14, due in large part to his power performance as a 19-/20-year-old in Double-A (PECOTA-adjusted ISO of .196). Guzman is so young and his body and baseball skills are still developing, so a 71% contact rate is not a chief concern at present. Strikeouts for a power hitter are to be expected, but a poor contact rate in conjunction with other red flags should raise concern.

  • Speed indicators (3Bs, SBs, SB%, GIDP): Above-average speed indicators are equated with athleticism and suggest that the player’s skill set is apt to age better than a Molina-like baseclogger. Granted, you shouldn’t ignore a lumbering slugger like Ryan Howard because he has few triples and steals, but a guy who’s stealing bases, avoiding hitting into double plays, and piling up extra-base hits tends to age well.

    These indicators were the sole reason that Erick Aybar was able to sneak onto the list at #50. While Aybar has shown he can hit for average (.316 career) while making good contact (88.6%), his ISO (.090) and BB/PA (4.7%) are mediocre. He helps mask those deficiencies by averaging 51 SBs per 162 games played, although his SB% is at just 65%. Aybar has also averaged 13 triples per 162 games played, and on an additional positive note, his BB/PA increased from 4.3% to 5.2% in the last year. A spike to 7-8% in 2006 could get him in the #30 range on the 2007 list.

  • Park-adjusted raw power indicators (ISO, Extra-Base Hit%, ISO per ball in play): Scouts say that power is often the last “tool” to develop, but an ISO of .200+ in an age-appropriate league is a good indicator. ISO might not be important as other factors on this list unless we’re talking about an “older” prospect. Rany Jazayerli points out the case of Edwin Encarnacion to illustrate the point:

    Encarnacion’s PECOTA-modified ISO:

    Year League          ISO
    2000 (GCL)          .051
    2001 (Rookie/Low A) .126
    2002 (Low A)        .168
    2003 (High A / AA)  .134
    2004 (AA)           .160
    2005 (AAA/Reds)     .222

    While maintaining a feeble ISO, it was Encarnacion’s other skills (defense, power, speed, etc.) that led to high rankings on previous BP lists. When you factor in his age in 2000 (17), a sub-par ISO can be overlooked in favor of other indicators. Now if a guy presents as a Burroughs clone in an age-appropriate league, a red flag will rise. One guy who’s coming close: Daric Barton (career PECOTA-modified ISO of .164). No need to panic on Barton quite yet though (BP didn’t–he’s ranked #18 on the Top 50), as he hit .310/.410/.491 in Double-A at age 20.

    Note also that in the heading for this section is the word “park-adjusted.” Brandon Wood hitting 43 home runs in the hitter-friendly California League ballparks is impressive, but not quite as impressive as if he had performed similarly in the pitcher-friendly Florida State League. Wood’s PECOTA card reflects this sentiment, as his raw numbers of .321/.383/.672 translate to a more reasonable and conservative .257/.309/.506. An 815 OPS is still solid for a SS, but those thinking that Wood can be a perennial 50-HR guy better think twice.


  • Age vs. peer group: Generally, a premium should be placed on players playing above their accepted age-appropriate level. Generally you like to see the following age/level proportions: Low A = 19/20, High A = 20/21, Double-A = 21/22, Triple-A = 22/23. This is why not much attention will be given by BP to college draftees who crush Gulf Coast League pitching, for example. Conversely, a teenager who is among the best players in Double-A or even High A warrants significant attention.

    The obvious man-child to highlight in this section is Delmon Young. What Young was doing in the pitcher-friendly Double-A Southern League (pursuing the Triple Crown) is nothing short of amazing. It is even more amazing to consider that he was doing it, before his promotion to Triple-A, at the tender age of 19/20. Other than a rough patch in Triple-A, there’s nothing NOT to like about Young. If he had had the year he did in 2005 at age 23, he’d still have been a top 20 prospect, but his age made him a no-brainer at age 20. Why? At such a tender age, it’s nearly a lock that his best is yet to come. Young’s body is still developing, and with additional muscle and game experience, he should get even better. If he’s this good now, wait until he turns 25. The anti-Delmon: Josh Willingham at age 27. Despite below average defense, his bat is good enough to be a top 15 prospect–if he were 5 years younger.

  • Plate discipline: While OBP is not all-encompassing in evaluating prospects, the ability to take a walk is a positive indicator that a player will have success against more-advanced pitching. Watching Vladimir Guerrero golf balls off his foot and over the wall isn’t something a young player should be trying to emulate. As a general rule, an OBP-AVG spread of .065 and .070 is acceptable. This translates roughly in a baseline BB/PA rate of 8.0-8.5%. While prospects often take time to turn raw power into home runs, plate discipline isn’t so easily learned. For every 20 Ruben Mateos and Reggie Abercrombies who never caught on, there’s probably one Brandon Inge. Inge’s plate discipline indicators seem to indicate that plate discipline can in fact develop later in a player’s career:
                OBP     OBP-AVG     BB/PA
    2001        .215     .035        4.5%
    2002        .266     .064        6.8%
    2003        .265     .062        6.6%
    2004        .340     .053        7.0%
    2005        .330     .069        9.1%

    Jeremy Hermida was off the charts in both plate discipline metrics, posting an AVG-OBP spread of .164 in his trip through Double-A in 2005 and a BB/PA rate of 21.9%. Hermida, though, is rated highly for other factors as well, but consider the case of teammate Josh Willingham. BP rates him #48, and it’s certainly not for his glovework or age (27). Clearly, Willingham’s high marks are predominantly a result of his plate discipline and power. By any measure, he’s been a high plate discipline guy in his 532 minor league games: .417 OBP and 19.3% BB/PA.

    There are several players on BP’s prospect list who could help their cause by improving in this area include Josh Barfield and honorable mentions Ronny Cedeno and Hanley Ramirez. Growth in their plate discipline will add more shine to their stars.

  • Position: Dayn Perry’s 2004 article “Rethinking the Defensive Spectrum” illustrates that since the turn of the century, the relative productivity by position goes like this: C – 2B – SS – 3B – CF – DH – RF – LF – 1B. Overall, the catching position is the least productive on a Runs/PA basis, while first basemen are the most productive. Simply put, all other factors (age, level, etc.) aside, a catching prospect with similar statistics as a first baseman is far more valuable.

    Take the case of Jarrod Saltalamacchia (BP’s #23 prospect). “Salty” put up a .314/.394/.519 line with a .205 ISO in High A while playing half his games in a tough pitchers’ park. A switch-hitting catcher with his offensive skill set is extremely rare, but due to the presence of Brian McCann and with questions surrounding his defense, a position change to the opposite end of the spectrum is a possibility. If he had the defense to match his bat and was guaranteed to remain behind the plate, he’d probably be a top-five prospect.

  • Defensive scouting reports: If a guy has a 950 OPS in an age-appropriate league, but scouts attribute the words “iron” and “glove” to his defensive skills, said prospect’s rating plummets. Conversely, superior defensive skills a la Ryan Zimmerman and Ronny Cedeno can help mask offensive deficiencies.

    Zimmerman checks in as BP’s #3 prospect due in large part to the multitude of praises heaped upon his glove. Baseball America has called him a “once in a generation” whiz with the glove. At the University of Virginia, Zimmerman showed good plate discipline and bat control while hitting .355/.401/.472 with a mediocre .107 ISO. While his ISO did increase to .170 in his final year of school, judging Zimmerman on the totality of his college offensive performance have been fatally short-sighted. To wit, he blew through the minors in 2005 and between Low A, Double-A, and the majors, Zimmerman had an ISO of .214.

  • Ability to handle same-side pitching: Demonstrating the ability to produce against same-side pitchers minimizes the chance that a player will be platooned in the future. It can be expected that going forward, this type of information will become more widely-available, but as of now, there isn’t the data to support considering platoon splits to be a critical factor. I suspect that notoriously extreme-split types like Hank Blalock and Eric Chavez also had troubles with southpaws in the minors, but despite that, they’re still among the game’s elite at third base.

Hitters Recap: The ideal hitting prospect? Delmon Young minus the Triple-A stats. The model prospect would put up ISOs of .220 or higher against an older peer group, make decent contact, run the bases well, play a premium defensive position and figure to stick at said position, command the strike zone and not have a history of injury (particularly hands and wrists for hitters–aka “James Loney Disease.”

Pitching prospects:


  • GB/FB Ratio: A high GB/FB ratio is an indicator that a pitcher is less apt to allow an inordinate number of home runs at the big league level. According to ESPN, there were 60,328 groundballs and 49,086 flyballs hit in 2005, for a ratio of 1.23.

    Among pitchers on the top 50 (or honorable mention), an average GB/FB ratio of 1.19 hurts Jon Lester somewhat in relation to other pitching prospects and could be a future trouble spot pitching in Fenway Park. Matt Cain‘s poor ratio of 0.60 is negated somewhat by the effects of AT&T Park, but could be an indicator of future trouble.

  • K/9 and K/BB: Simply put, pitchers show dominance by striking guys out. The ability to overwhelm hitters at the minor league level is an excellent indicator of future success. If a pitcher is consistently throwing strikes and striking batters out, it usually indicates good movement and velocity while being able to throw at least two pitches for strikes. The baseline for K/BB is 2:1, but your top prospects will be at 3:1 or better (Francisco Liriano was at 4:1). The baseline for K/9 is 9.0–we like to see pitching prospects striking out a hitter an inning or more. Also, excellent K/9 and K/BB rates increase in prospect-ranking relevence as a pitcher ascends the minor league ladder. A guy can get by on mediocre stuff at the lower levels if he had good polish and command. Not so much once he hit Double-A and above.

    There are 15 pitchers (13 starters, 2 relievers) on the Top 50. Of the 15, only Jeremy Sowers (#17), Paul Maholm (#38) and Jon Papelbon (#36 – 8.6 K/9) failed to strike out a hitter per inning. Matt Cain’s pedestrian (for an elite pitcher) K/BB rate of 2.2:1 is troublesome, but other factors helped balance his negatives. Sowers compensates by exercising pinpoint control (5:1 K/BB) and by keeping the ball in the park (just six HR allowed in 159 1/3 IP). Maholm keeps the ball on the ground (2.25 GB/FB ratio between two levels), and will benefit more from a strong defense than other pitchers.

  • Platoon splits: The ability to fare well against both right and left-handed hitters prevents major league managers from stacking the lineup against the pitcher. The recent signing of Jeff Weaver by the Angels, for example, bodes well for the likes of Mark Teixeira, Hank Blalock, Dan Johnson and Eric Chavez. Weaver’s splits are among the most extreme in the game. Over the last three years, he’s held RH hitters to .238/.277/.355 while lefties teed off to the tune of .309/.369/.506. It’s difficult to evaluate minor-league pitchers in this category due to the relative lack of information, but a right-handed pitcher who has a good “reputation” and “nice upside” but fails to get left-handed hitters out at an adequate clip is in for trouble at the highest level.


  • Health history: Scores of young pitchers have overcome Tommy John surgery and various maladies to become big league starting pitchers, but a poor track record health-wise is not something you want to see. These days, the Tommy John recovery success rate is so high that you almost don’t mind a young pitcher getting it done, but pitchers that spend parts of every year on the DL (stiff shoulder, tender elbow, sore triceps, etc) are at risk for future ineffectiveness and ultimately, surgery.

    Greg Miller‘s stuff, performance in Double-A as an 18 year-old (1.01 ERA and 40 K’s in 26 2/3 IP), K rates, etc. would leave him with a chance at ranking in the top five overall prospects, but he’s been hurt for the better part of two full seasons. Another Miller, the Indians’ Adam, would similarly find himself way up the prospect food chain if not for recurring elbow problems. Greg Miller has undergone two shoulder surgeries and altered his arm slot while publicly claiming that he may end up as a reliever. Adam Miller missed the first 2 ½ months of 2005 and never had surgery on his balky elbow, leading to concerns that it could flare up again down the line. Cole Hamels is another guy who could rocket up this list with a healthy 2006.

  • Scouting reports: You always like to see a young pitcher with a minimum of one “plus” pitch and solid secondary stuff. Lots of guys can throw 95, but unless a pitcher has good breaking stuff and/or a solid change, hitters (especially at the upper levels) will sit on the fastball. It is the opinion of Rany Jazayerli that a scouting report for a pitcher is 2-3 times as important as for hitters. A guy with an 85-mph fastball, mediocre breaking stuff, and no change isn’t worth paying attention to, no matter his numbers. On the other hand, if a guy throws an average 90-mph fastball but has solid secondary offerings and/or excellent mound presence and intelligence then yes, his numbers are meaningful, as a pitcher with that profile fits the bill of a major-league pitcher.

    Francisco Liriano’s fastball, slider and change all have a “plus” scouting rating, something that you really don’t see often. It’s the raves of the scouts and managers that have seen Liriano that gets him to BP’s #4 position while a guy like Chuck James, with nearly equally-impressive numbers, fail to even crack the honorable mention list. Let’s look quickly at each man’s 2005 minor league numbers:

                H/9      K/9    BB/K   GB/FB
    Liriano     6.8     11.0    1:4.1  1.58
    James       5.7     10.8    1:5.4  0.35

    Until you get to the final column, it doesn’t appear that Liriano has much on James. James’ GB/FB rate though is simply unsustainable at the big-league level. Factoring in his stuff, described by most as unremarkable, makes us question how much of an advantage his excellent command and ability to keep hitters off-balance will be once big league hitters get a good look at him. Liriano though not only strikes out a lot of hitters, but when they do make contact, there is a good chance that the ball will be hit on the groud.

  • Age vs. peer group (See the Hitting Prospects section): Simply put, a 23 year-old college pitcher dominating the Sally League is far less impressive than a 20 year-old holding his own in High A. Rich Hill turns 26 in March, making his performance last year less impressive than it would have been had he been 23. Indeed, when Hill reached the majors, he found the going a lot rougher while putting up an 8.62 EqERA, aided by 17 walks in 21 IP. He’s still a very good prospect due to the command and dominance he showed this year in the minors (13.4 K/9), but he needs to prove it against major league hitters to make believers out of a lot of folks.

    Philip Hughes has seen as much time on the trainer’s table as he has the mound in his first two seasons as a professional. A stubbed toe, elbow tendonitis, and sore shoulder are among the maladies that have plagued the former 1st rounder. Still, PECOTA and Hughes have a love-fest going on. Not only is he ranked just behind Liriano in terms of peak value, he’s also most comparable to Jake Peavy. Elite company indeed. Hughes earns high marks for his performance as a teenager, striking out over a hitter per inning while holding SAL and FSL hitters to a line of .182/.245/.215. You don’t see a .215 SLG-against very often, and it’s a result of allowing just one longball in 86 1/3 IP. One final note: the Yankees have yet to even allow Hughes to throw his supposed best pitch, a slider. Look what happened when Felix Hernandez had the reins loosened in 2005. Hughes will have similar freedom in 2006 and is a healthy season away from elite status.

Pitchers Recap: The ideal pitcher is pretty simple: look up a Felix Hernandez report. Outside of that, you like to see a pitcher with a clean health history, at least two “plus” pitches and a decent changeup, the ability to strike out a hitter per inning while maintaining a 1:3 BB:K rate, and a GB/FB rate of 1.20+ A track record of consistent improvement against older competition and the ability to get both same-side and opposite-side hitters out on a consistent basis are also key indicators.

Wrap-up: With both pitchers and hitters, we prefer to see more than one standout season in their dossier and success in the high minors. Consistency and improvement should be noted from year to year. Translating tools into performance is critical, as all the tools in the world are meaningless without the associated production, or a prospect could risk having a Ruben Mateo-like flameout. One final note: recent draftees from the college and prep ranks shouldn’t be ignored due to a lack of an analyzable record of performance, so the bias should be towards high picks such as 2005 picks Justin Upton and Alex Gordon. Such guys should have a track record going back to their early days of high school or college that is indicative of future success.

David Regan is a freelance writer residing in Southern California. You can contact him with feedback and questions via e-mail here.

Thank you for reading

This is a free article. If you enjoyed it, consider subscribing to Baseball Prospectus. Subscriptions support ongoing public baseball research and analysis in an increasingly proprietary environment.

Subscribe now
You need to be logged in to comment. Login or Subscribe