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April 4, 2012

Raising Aces

Pitchology 101

by Doug Thorburn

My name is Doug, and I am a baseball junkie.

It all started with an eight-year old kid and an innocent pack of Topps baseball cards. There must have been something laced into that stale piece of gum, because my formative years are nothing but a haze of cardboard stats, makeshift whiffleball fields, Mark McGwire moon shots, and heated Saberhagen-Valenzuela duels in RBI Baseball. By college I was on to the hard stuff, with fantasy baseball teams stretching as far as the eye could see, buoyed by the mass consumption of designer statistics like VORP, PAP, and EQA.

After graduation, I decided to turn my baseball addiction into a career and started climbing the ladder with a club in the Pacific Coast League. It was there that I learned that players will show up early to the ballpark just to play cards in the clubhouse, that front-office types will decorate their office walls with more posters than a college dorm room, and that gameday columnists will have three-quarters of an article written before they get to the stadium. I also learned to recognize my own shortcomings when analyzing the game, the most glaring of which involved the mystery of pitching mechanics. 


Mechanical Efficiency and Pitcher Signature
Pitching mechanics form the backbone of player performance, and a pitcher's delivery will ultimately determine his velocity, movement, and command of his arsenal. There is a laundry list of pitchers who had elite talent but never approached their ceiling due to mechanical inefficiencies that blocked their ascent. Such flaws are often correctable. However a player's “signature” can present major obstacles to instruction, as some aspects of the pitcher's delivery are hard-wired to the athlete and thus borderline uncoachable. Altering a player's mechanics can be awkward in the early stages, as a pitcher re-trains his muscle coordination, but the influence of signature can make it nearly impossible to correct some issues without sacrificing effectiveness. Handedness is an extreme example of player signature—a right-handed pitcher is not about to become ambidextrous just to score a platoon advantage.

The Kinetic Chain
Pitching involves precise coordination of linear and rotational movements, and an efficient delivery will follow a very specific progression. The entire pitch sequence is executed in under 1.5 seconds, and the key to a player's success lies in his ability to repeat his motion with consistent timing. One underlying concept of the kinetic chain is that a weak link will manifest itself later in the delivery, and the coaching implication is to start at the setup and work down the chain when addressing mechanical inefficiencies. Often, the best way to fix a player's release-point consistency is to make an adjustment to his setup position, after which the rest of the components will fall into place. There are several links in the kinetic chain, and we will anchor on four major checkpoints in the delivery: set-up, maximum leg lift, foot strike, and release point.


Every play on the diamond begins with the man on the mound, and my limited understanding of pitch execution was maddening. I had pitched a bit in high school, had watched countless Triple-A hurlers from the press box, and had even scouted a number of amateur players. Yet I had no clue how a pitcher's mechanics actually contributed to his performance on the field. It was as if I had feasted at the buffet of baseball information but somehow missed out on the prime rib at the end of the table. Nothing short of addictive compulsion drove me to the National Pitching Association to work with pitching mastermind Tom House, whose scientific approach to the sport would trigger a reformation of my baseball awareness.

What had once been a jaded perception of pitching evolved into an aggressive pursuit of mound knowledge once I joined the NPA. The job provided access to the foremost experts on pitching, ranging from Hall of Fame players to renowned orthopedic surgeons, and I was trained to wear the lens of a pitching coach. Most of my time was spent consumed with the motion-capture system that we had on-site in San Diego, analyzing pitcher mechanics using the same hi-tech equipment as movie studios and video game companies. The technology allowed me to break down a delivery at 1,000 frames-per-second, to view pitches from virtually any angle, and to make strategic measurements for a bevy of functional variables. After five years spent analyzing thousands of pitches from both the bullpen and the computer, I had learned to diagnose mechanical strengths and weaknesses faster than Doogie Howser on a two-liter of Tantrum, but nothing sealed the deal quite like the experience of throwing a baseball pain-free for the first time since blowing out my shoulder as an 18-year-old.


A pitcher's set-up strategy has a ripple effect that reaches all the way to release point. Balance is an integral piece of the mechanical puzzle throughout the delivery, and efficient pitchers will begin with a balanced set-up, in an athletic position with some bend in the knees, and with the head above the athlete's center-of-mass. Signature plays a significant role in determining the ideal set-up position for each player, and though some coaches will adhere to cookie-cutter rules such as “left-handers pitch from the first-base side of the rubber,” a blanket approach can be devastating when applied to the wrong pitcher. The ideal starting position on the stripe is best determined by looking at the pitcher's back foot at release point and making a lateral adjustment so that the drag foot finishes on an imaginary centerline that runs from the middle of the rubber to home plate.

Maximum Leg Lift
Maximum leg lift is often referred to as the “top” of a delivery, and pitchers such as Cole Hamels demonstrate the strength to maintain balance along with the flexibility to sustain a high leg kick. Some pitchers will drift back toward second base and/or “stop at the top” to gather balance. However, such strategies are mechanically inefficient with respect to generating momentum. A player can harness greater kinetic energy from the set-up position, with two feet planted on the ground, while initiating movement toward the target.

Pitchers such as Felix Hernandez and Zack Greinke employ a corkscrew-like twist as they approach max leg lift and uncoil with a burst of forward momentum, though most of these pitchers need to ditch the corkscrew when pitching from the stretch due to time constraints. Tim Lincecum demonstrates that the best way to use the corkscrew is to pair it with an initial surge that is directed at the plate, combining the best of both worlds to create a tremendous stride and a deep release point. The corkscrew is also an extreme example of how a pitcher can change speeds with his delivery, as many hurlers will kick their momentum into second gear after maximum leg lift.


My greatest takeaway from the NPA was the strategic integration of objective and subjective data to improve player health and performance. Theories were driven by observations from the bullpen, and after crunching the numbers in our motion analysis system, the findings were re-applied to the field through various drills and coaching techniques. The motion-analysis stats helped to validate some of our hypotheses about pitching and to challenge some long-held beliefs in baseball. We studied the best pitchers in the game, comparing their deliveries to discover any mechanical ties that would bind baseball's most dominant arms. Our research culminated in a book that leaned on motion-analysis data to tackle the conventional wisdom of pitching, and we used photographs to visually demonstrate the mechanical similarities of five elite pitchers with superficially diverse deliveries.

A pitcher's mechanics can vary over time, and though a single evaluation might have a brief shelf-life, mechanical baselines are relatively persistent. Some of the details are easy to assess, even when consumed in small sample sizes from the convenience of a couch. Watch Brandon Morrow pitch on any given day, and odds are that his mechanics will vary widely between the stretch and the windup and that he’ll struggle to harness the timing of his delivery with a slide step and runners on base. Those issues help to explain the discrepancy between Morrow's ERA and his FIP, as well as his inability to keep the ball down when pitching from the stretch. On the other hand, we have Aroldis Chapman, who struggles to repeat his delivery regardless of the situation on the bases. Chapman's inconsistent timing of his high-octane motion leads to an erratic release point, and nobody in the stadium knows whether the next pitch will be over the plate or in Mr. Reds' ear-hole.


Foot Strike
Defined as the moment that the landing foot comes into contact with the ground, foot strike marks the completion of the chain-link for stride. Ideally, a pitcher will avoid the imbalanced approach of Carlos Marmol by establishing a solid foundation at foot strike, with stride length cemented as the rotational elements of the delivery start to fire. King Felix has a strong stride and displays opposite-and-equal arm angles as he approaches foot strike, a technique that adds to his dynamic balance. 


A mechanically-efficient pitcher will wait until after foot strike to trigger trunk rotation, allowing the hips to rotate and increasing the angle of hip-shoulder separation. Having both feet planted is essential for generating power, and one can imagine how a hitter's bat-speed would be crippled if the batter initiated his swing mid-stride, with the front foot still off the ground. Hip-shoulder separation is a key component of the velocity equation, and though the majority of major-league pitchers achieve between 40 and 60 degrees of separation, some of baseball's hardest throwers have been able to break that ceiling, including Nolan Ryan, Stephen Strasburg, and the aforementioned Mr. Chapman.


Release Point
A successful release point is the consequence of the preceding elements in the kinetic chain, and the quarter-second time period between foot strike and pitch release presents the greatest opportunity for error, considering the convoluted series of actions that take place within that minuscule timeframe. The ability to repeat mechanical timing is at the heart of pitch command, and all of the gears have to click in order to produce the same release point on every pitch. A pitcher with strong balance into foot strike will have an easier time maintaining his mechanics as the throwing arm whips through the batter's visual window, with the goal of having shoulders square to the target during the “arm-cocking” phase of the delivery (a.k.a. maximum external rotation of the throwing arm), as exhibited by Clayton Kershaw.

Ideally, a pitcher will keep his head over his center-of-mass with minimal tilt of the spine as the arm accelerates forward, and strong-posture pitchers such as Roy Halladay will reap the benefits at release point to bolster pitch command. The shot of Jered Weaver provides a counterexample of a pitcher with considerable spine-tilt as he releases the baseball, though Weaver is an exception to the general rule that poor-posture pitchers lack command.


Weaver is the rare pitcher who can consistently repeat an 11 o'clock arm slot, and he finds his release-point position despite the considerable tilt to his glove side. Arm slot is a function of both mechanical efficiency and player signature, as it is the net result of a pitcher's posture combined with a biologically-driven angle of shoulder elevation (a.k.a. abduction). There is a natural trade-off that exists between height and distance at release point, as a pitcher who bends his spine to achieve a higher arm slot will cost himself  distance at release, resulting in lower perceived velocity and earlier break on his pitches.


Carl Sagan said that “science is a way of thinking much more than it is a body of knowledge,” and a scientific approach to baseball requires an open mind in order to prevent previously-accepted theories from forming a barrier to discovery. To evolve as a pitching coach, I had to open my awareness to new ways of absorbing baseball, as I had been unknowingly wearing blinders from 20 years of watching the game from a single perspective. My world was rocked the first time I spent an entire ballgame focusing on just the catcher's mitt and was clued in to the functional difference between pitch command and control. The basis of the NPA approach was that Tom was willing and eager to prove himself wrong in the name of scientific progress, and half of the theories that we challenged were coaching techniques that he advocated in the 1980s.

Through the study of pitchology, we can understand the why and the how that exist behind the numbers. We can evaluate the reasons why some pitchers consistently post “lucky” BABIPs, or how “downhill plane” plays a role in the hitter-pitcher interface. “Raising Aces” is dedicated to the proposition that all pitchers are not created equal and that individual context is crucial to understanding the path of a player, including aspects of mechanics, signature, size, and stuff. The ominous world of pitching is full of theoretical sand traps, and modern research has uncovered the evidence to challenge some deep-rooted beliefs, including but not limited to:

1)     Release-point height is overrated, while release-point distance is undervalued
2)     The slide step may be much more harmful than it appears
3)     The majority of major-league pitchers will miss the majority of their targets
4)     Pitching with “effort” is not only acceptable but is often encouraged in the right context
5)     Pitcher injuries rarely have an isolated cause and typically involve a combination of factors

Consider the above list a syllabus for the semester. Class dismissed. 

Doug Thorburn is an author of Baseball Prospectus. 
Click here to see Doug's other articles. You can contact Doug by clicking here

23 comments have been left for this article. (Click to hide comments)

BP Comment Quick Links


This is great. The photos were very helpful in illustrating your points. Looking forward to future articles.

Apr 04, 2012 06:01 AM
rating: 6

Doug, at what point in the delivery should the back knee bend toward the target? My son seems to be inconsistent with that piece of the delivery.

Great article. Thanks!

Apr 04, 2012 06:32 AM
rating: 0
Doug Thorburn

The back knee will turn naturally during hip rotation, beginning just after max leg lift and facing the target after foot strike.

Does the issue happen from both the stretch and the windup? Does your son have the same problem when playing catch, or making throws to first base? A lot of young players have great natural throwing mechanics from shortstop, but they try to get fancy on the mound with poor results.

Apr 04, 2012 12:23 PM
rating: 0

At some point this semester I'd like your thoughts on Mike Marshall's approach vs. Chris O'Leary and I think there is a lot of confusion regarding "fingers on top of the ball" and "pitching from the ear" and lastly "don't drop your elbow" at the youth pitching level. I'd like to see those addressed as well.

Great article. Thank you.

Apr 04, 2012 06:35 AM
rating: 2

One thing that I would find useful with a lot of this is if you could tell us a little about the evidence that supports your work. I find that helps me to make up my own mind more effectively, especially as this can be an area where a lot of assertions are made without much supporting evidence.

Apr 04, 2012 07:14 AM
rating: 5
Doug Thorburn

Great point Behemoth, and I know that one of the frustrations with pitching mechanics is that there are so many "experts" with different opinions, some of whom spend a great deal of energy insisting that they are right (I have the same problem when seeking landscaping advice).

One of the great challenges in coaching/scouting is to relate with words what can be seen with the eyes, and I will lean on visual evidence to help bridge that gap (photos, videos, and game footage). I will also use a combination of objective and subjective data to explain my evaluations, in addition to assigning grades (20-80 scale) for individual pitcher mechanics.

I hate to play the "shameless plug" card, but the statistical evidence can be found in our book - "Arm Action, Arm Path, and the Perfect Pitch." The book marked the first time that motion-analysis data of pitchers was made available to the public, and several of these concepts were investigated.

I greatly encourage the readers to join in the investigation of pitching, rather than take my word for it. For example, I will be breaking down Yu Darvish after his first MLB start, and one can set the DVR or check MLB.TV for Rangers-M's on 4/9 in order to follow along with the analysis.

Apr 04, 2012 19:05 PM
rating: 4

Great article! This will fill a nice nitch for BP. It seems that there is so little fact and scientific based discussion of pitching. Another win for BP!

Apr 04, 2012 09:16 AM
rating: 3
Other readers have rated this comment below the viewing threshold. Click here to view anyway.

Nitch? Seriously?

Apr 04, 2012 09:46 AM
rating: -8

Quit yer bicheing

Apr 04, 2012 13:08 PM
rating: 5

How does the height of a pitcher's leg lift affect the forces delivered horizontally? The leg goes up, the leg goes down and then the pitchers center of gravity moves forward - seems like wasted energy to me.

Apr 04, 2012 10:08 AM
rating: 0

Coach Adams: There is a problem with leg lift especially when you consider pitching from the stretch; however, I think some pitchers use leg left as a trigger and/or a pre-stretch for a long stride. If the leg lift is following with a quick and explosive move towards the plate, it's not really wasted. We bring our arm back before we throw and our leg back before we kick so doesn't the leg lift work in the same way?

Apr 04, 2012 10:42 AM
rating: 0

Not exactly - We bring our arm back because of the principle in physics that says, "for every action, there is an equal and opposite reaction". You bring the arm back so you can drive it forward. Lifting the leg provides no equal reaction as it goes down, then forward. It's not "quick and explosive", especially from the wind-up. The author says "maximum leg lift", not "maximum leg back". I'm not an expert, just an observer so I'll be curious about the science or "evidence" that supports the work in this series, as well.

Apr 04, 2012 11:07 AM
rating: 0
Doug Thorburn

Good question, coach.

Leg lift provides the opportunity to get the most out of the horizontal forces that are generated. A taller leg lift will keep the leg off the ground longer while the pitcher approaches foot strike, thus lengthening his stride (which is a good thing as long as a pitcher maintains balance).

There is also a big distinction between pitchers who drift back to start their delivery and those get going straight toward the target. In the case that you describe - "the leg goes up, the leg goes down and then the pitchers center of gravity moves forward" - energy absolutely is wasted. But a pitcher who makes the first movement toward the plate is taking advantage of the setup position to harness more kinetic energy, which combined with a high leg lift will create an awesome stride.

When watching games on Opening Day, take a look at pitcher stride length from the windup vs. the stretch. I think you'll notice that pitchers who use a slide step tend to have a shorter stride from the stretch than from the windup, due to the lowered leg lift and abbreviated timing into foot strike.

Apr 04, 2012 12:05 PM
rating: 0

Okay... I'm not a pitching expert, just a youth coach and fan, but when I look at Lincecum pitch he does have a huge leg lift, but then he drops his foot all the way back down and it barely skims the surface of the mound all the way to the end of his huge stride. So the leg lift isn't making room for the stride... what is it doing if it's not involved in the coiling process?

Apr 04, 2012 13:15 PM
rating: 0

Felix Hernandez seems very similar in the last 3/4 of his delivery.

Apr 04, 2012 13:39 PM
rating: 0
Doug Thorburn

The leg lift does "make room for the stride," in the sense that Timmy is moving forward (toward the target) during the lift phase, and his center of mass travels further than it would if he had a lower leg lift (prior to getting into the "skim" phase). The "skim" technique adds even more stride length, and there are other pitchers who employ that strategy as well, but the skim is made possible by the preceding links in the kinetic chain - if Lincecum lacked the combination of balance, momentum, and lift, then he would not be able to take the same advantage of the skim technique.

Keep in mind that max leg lift is not an absolute determinant of stride length, but rather one of several factors that play a role. Lift height is a potential mechanical advantage that is trainable from a coaching perspective, though the aspect of signature dictates that some players have different styles of lift - i.e. pitchers who bring the lift foot back toward 2nd base are less dependent on lift height to extend stride.

Apr 04, 2012 16:01 PM
rating: 0

I'll watch for differences in stride distance but my sense is that pitchers have landing spots - irrespective of wind-up or stretch - that is very consistent as evidenced by the "holes" they create on the mound.

Apr 04, 2012 15:01 PM
rating: 0
Doug Thorburn

I agree with the "landing spots," though there is a wide variance in consistency/size of those landing areas from player to player, and many pros have very different landing spots from the stretch and the windup (i.e. multiple "holes"). On one extreme you have Nolan Ryan, who was known for landing in the same cleat mark on every pitch, and on the other you have amateur players who can turn a mound into a mine field.

The best pitchers will dig "holes" that are much smaller in area. It's like a drummer with a new set of heads - a great drummer will hit virtually the same spot every time and leave very few visible marks, but an inexperienced drummer will leave stick-marks in a random pattern all over the drumhead.

Apr 04, 2012 16:11 PM
rating: 0
Ian Miller

Incredibly rich article. Just finished my 1st pass though it, and will be back several more times, I expect, to digest all the wisdom herein. Thanks for sharing it!

Apr 04, 2012 12:21 PM
rating: 5

Doug- Awesome article, looking forward to the rest. Your childhood sounds a lot like mine, RBI baseball, stale baseball card gum, Bash brothers. I own a baseball training company now and am a pitching coach by trade. My dad bought me Tom Seaver pitchers bible when I was in HS and have followed Tom House since. I dont agree with 100% of what he says but agree with main areas and have used countless NPA drills with my pitchers. I assume you are going to cover deceleration?

Apr 04, 2012 20:37 PM
rating: 1

This is great; don't know how I missed it the first time around. I'm very much looking forward to following this series, and it's only a matter of time before I buy Doug's book.

Apr 12, 2012 04:28 AM
rating: 1

This has always been a topic that is fascinating to me. can;t wait for more. I also can't believe I missed this the day it was published.

Apr 12, 2012 21:23 PM
rating: 0

This article was excellent.

Apr 16, 2012 12:16 PM
rating: 0
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