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Position Statement

Updated 2015.9.11

I have been studying pitching mechanics since early 2005, when one of my 4th grade pitchers suffered an elbow injury in the first game of the season and after a seven-month layoff. In the nearly ten years since that day, I have been studying pitching mechanics, trying to do everything I can to keep the pitchers I teach and coach (including my own sons) healthy.

Based my years of research into physiology and biomechanics, I have come to a number of conclusions about the topic of proper throwing and pitching mechanics.

Let's start out by sticking to the facts and then get into the opinions that I believe that those facts can reasonably lead us to.


Conditioning is something that is proposed as both the cause of and the solution to the pitching injury epidemic. It can't be both, so what are the facts?

  • F01. FACT: Kids are not short adults. Because they are growing (usually rapidly), kids' bodies are fundamentally different than the bodies of adults. For instance, kids have weaker cartilage in many places that are solid bone in adults. Kids' bones are also peppered with growth plates, weak spots where the bones grow.
       There is nothing you can do about these differences other than be patient while kids are growing and not over-load them, especially during growth spurts.
  • F02. FACT: While conditioning is the best tool for adults, it is only of limited value for kids. There is little doubt that some conditioning is good for adults and more conditioning is usually better.
       For adults.
       However, due to their bony structure, and the presence of growth plates in particular, there are limits to how much conditioning the bodies of kids can tolerate. What's more these limits are essentially unknowable and will vary from kid to kid and from month to month.
  • F03. FACT: "Kids don't throw enough" is true, to a point (but probably not in the way that many people think). There is a difference between just throwing the ball around with, or even pitching to, your friends in a park and playing a full weekend (or worse, week) of organized, often highly competitive baseball. The difference between 40 years ago and now likely isn't that kids aren't throwing as much as we did back in the day. Rather, the difference is that kids today throw far more in highly structured, and often highly competitive and intense, settings. As a result, their bodies are under increased levels of stress.DRS

Looking for Differences

For much of my early career I was a troubleshooter; I was the person that my employers called when their systems were broken and they needed someone to figure out what was going wrong.

The first rule of troubleshooting a system, especially one that was previously working well, is to figure out what has changed. The same principle of looking for the differences can be applied to troubleshooting the problem of pitching injuries.

  • F04. FACT: The way throwing and pitching are taught has changed. When I was a kid, growing up in the 1970s and early 1980s, most kids weren't taught how to throw. Instead, you were given a glove and a ball and played catch with your parents and your friends. In most cases, that progressed to pitching to your friends, emulating your favorite pitcher.
       That isn't how kids are taught to throw today.
       Instead of just gripping and ripping the ball, most kids today are taught using any number of cues, cues that I believe are problematic and that I discuss at length in Killer Cues.
  • F05. FACT: The cues that are used to teach throwing and pitching are producing different arm actions and timing than you saw in pitchers from 20 years ago or more. If you compare video clips and still pictures of older pitchers and contemporary pitchers, you will observe a number of differences, including...
    • More pronation at the high-cocked position.
    • Less external rotation at heel plant.
  • F06. FACT: Ballplayers throw harder than they used to. The average fastball velocity has increased over the years.AFBV That is an issue because, as fastball velocity goes up, so too does the load on the elbow and the shoulder.
  • O01. OPINION: You will not be able to understand what is happening and why unless you study what is being taught at the youth levels and how that has changed over the years. As I explain in Pitching MRSA, if you study the history of how throwing and pitching are taught, you can trace the introduction of a number of instructional innovations.
  • O02. OPINION: The problem isn't that we AREN'T teaching kids to throw. Rather, the problem is that we ARE teaching kids to throw and HOW we are teaching throwing. The way that kids are being taught to throw, while effective in terms of increasing velocity, is problematic in terms of the risk of injury.
  • O03. OPINION : The way that kids are being taught to throw, much less to pitch, is a (big) part of the problem. As I explain in my piece on the Killer Cues, there are numerous problems with how ballplayers are being taught to throw.

Breaking Balls
(Curveballs, Sliders, Cutters, Etc.)

Given that breaking balls are often blamed for the pitching injury epidemic, let's go over some of the facts about them.

  • F07. FACT: Nobody (really) knows whether curveballs are a problem or not. While many studies have been done about curveballs, and these studies suggest that the curveball is not the problem that many people think it is, the problem is that these studies are poorly controlled. Instead of defining what a curveball is, studies to date largely just asked the subjects to throw what they call their curveball. In my opinion, that creates a huge opportunity for confounding, where curveballs can be mixed in with sliders (and fastballs, change-ups, and everything else). To answer the question of whether curveballs are actually a problem, at a minimum the speed and break of the pitch needs to be captured and compared to the pitcher's fastball.
  • O04. OPINION: The connection between curveballs and injuries is real, but is due more to correlation than causation. In my experience, most rec pitchers tend to throw just fastballs. At most, top rec pitchers (most of whom also play select) will throw one or two curveballs to a batter, largely just as a show pitch. It isn't until pitchers enter higher-level select and/or travel programs that they start throwing multiple pitches. Of course, kids who play in high-level select and/or travel programs will also tend to play upwards of 60, 80, or more games per year, making overuse the more likely culprit.
  • O05. OPINION: Sliders are more dangerous than curveballs. At the youth level, sliders (deliberate or not) tend to be thrown with fastball arm speeds whereas curveballs tend to be thrown with slower arm speeds. That is significant because the lower the arm speed, the lower the stress on the arm. Jeff Zimmerman's piece Curveball and Slider Pitchers and the DL also discusses the fact that major league pitchers who throw more sliders are more likely to end up on the disabled list.
  • O06. OPINION: It makes sense to teach middle school ballplayers how to throw a curveball. In my experience, most pitchers who are older than 6th or 7th grade have experimented with throwing a curveball. In most cases, they throw what I call a turn the doorknob slider, where they rotate their wrist clockwise through the release point. Because of my concerns about the slider, I believe it makes sense to teach middle school baseball players how to throw an actual curveball in order to reduce the likelihood that they will accidentally or deliberately throw a turn the doorknob slider.

Inverted W

Given that I have gained most of my press as a result of my research into the Inverted W and related arm action flaws, I should probably address that topic and make clear the current state of the science.

  • F08. FACT: The problem with the Inverted W isn't the position itself, but with the timing problem that the position tends to create. As I discuss in my piece on The Science Behind the Inverted W, the Inverted W was studied in a piece entitled Early Cocking Phase Mechanics which was commissioned by Dr. Weimi Douoguih, Medical Director for MedStar Sports Medicine and Medical Director for the Washington Nationals.
  • F09. FACT: When I first noticed the arm action pattern that is now known as the Inverted W, I called it "The M." I then found it that Paul Nyman was describing and teaching it as the Inverted W, so I used his term since it was already out there and was the term that people were most familiar with.

I bring up the Inverted W not to toot my own horn or to beat a dead horse, but because, in my opinion, the lessons that have been learned about the Inverted W are relevant to the pitcher injury epidemic. In particular, the problematic thing about the Inverted W is the timing problem that it tends to create, and timing problems are also a result of many of the Killer Cues.


As a result of my years of research into the topic, I have come to hold a number of opinions about the state of the art of throwing and pitching mechanics in general and the pitching injury epidemic in particular.

  • O07. OPINION: Pitchers don't get hurt because their mechanics change. Instead, pitchers get hurt because their mechanics weren't good to begin with. In many cases, when pitchers get hurt, the first thing that pitchers and their coaches do is they look for something that changed. However, as in the case of Mark Prior's pitching mechanics, in most cases you won't find significant differences between pitchers' mechanics pre and post injury, even if you look years in the past. That strongly suggests that the problem isn't due to pitchers changing their pitching mechanics, but to problems with their original pitching mechanics.
  • O08. OPINION: The problem isn't that pitching coaches don't know what they are talking about when they talk about proper pitching mechanics. Instead, the problem is that for years they have been optimizing pitching mechanics for velocity and have effectively ignored the topic of injury risk. At the end of the day, I think the problem with Mark Prior's pitching mechanics was that they were perfect for creating velocity, but ignored the question of injury risk and the loads the body can handle without breaking down.
  • O09. OPINION: In most cases, problematic pitching mechanics take time to take their toll, which is why the connection between the mechanics and the injury often isn't made. In the meantime, the pitcher gets a pretty much immediate performance boost, which is why these pitching mechanics are taught.
  • O10. OPINION: Just because your pitching mechanics enable you to throw hard, it doesn't mean that your pitching mechanics are proper or even good.
  • 011. FACT: "Proper Pitching Mechanics" is a problematic phrase because it means different things to different people. As I discuss at length in my piece on Proper Pitching Mechanics, the problem is the word "proper."
       I define "proper" as mechanics that lead to pitchers who are both dominant and durable. Unfortunately, too often, and increasingly, "proper pitching mechanics" are simply those pitching mechanics that let pitchers (often quickly) throw harder. Similarly, too often people assume a pitcher's mechanics must be proper if he is throwing hard.
       However, in my experience, increasingly those high(er) velocities are being achieved by problematic cues, drills, and/or movement patterns.

For More Information

The EpidemicIf you are interested in learning more about what I believe are the roots causes of the pitcher injury epidemic, and what I believe can be done to reverse the trends we are seeing, I have put together a webbook entitled The Epidemic.


DRS. See the work of Dr. Robert Sapolsky on the effect of stress and stress hormones on the body, especially growing ones.

AFBV. Does pitching velocity matter?

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