> Essays > Mark Prior's "Perfect" Mechanics

Mark Prior's "Perfect"
Pitching Mechanics

Updated 2015.03.03

One thing that is holding up the adoption of the science (and yes sometimes art) of pitching mechanics analysis is the case of Mark Prior. Pretty much whenever someone, whether it's me or someone else like Kyle Boddy, makes a point about some pitcher being an injury risk due to their questionable pitching mechanics, someone inevitably jumps in with a variation of...

But didn't everyone think that Mark Prior had perfect pitching mechanics? You pitching mechanics guys clearly don't know what you're talking about.

In order to try to advance the discussion, and hopefully increase the number of people who believe that there is in fact a relationship between pitching mechanics and injury rates, let me tell you what I know about the whole Mark Prior perfect pitching mechanics fiasco.

Who Said What, When?

In order to inject some facts into the debate, let's first go back to the original sources. An article in the December 2002 issue of Baseball Digest written by Greg Couch contains the following comments about Mark Prior and quotes by Tom House...

"Mark is the real deal," said Tom House, a longtime major league pitching coach who worked privately with Prior for years. "Of the hard throwers, he's right up there with the (Nolan) Ryans, (Roger) Clemenses."...
House is a new-age coach, relying on coaching and playing experience and also his Ph.D. in psychology. He has taken all that science—computer, medical, nutritional and psychological—can offer to come up with a plan for developing pitchers...
"Mark has been exposed to, and taken advantage of, the best research available," House said. "He has been the poster child for what is, objectively, non-traditional baseball knowledge. He's not going to fail."...
House films pitchers at 1,000 frames a second, then downloads into his computer. That way, he can slow down a pitcher's motion and find exactly where any non-productive movements might be. Of 600 pitchers in House's computer, he said, Prior has the best mechanics after Ryan, Clemens, Randy Johnson and Curt Schilling...
His mental makeup, nutritional balance, everything else? Off the charts...
"He has all the pieces," House said. "Nolan Ryan (who worked with House) had some of the pieces. Other guys have had some. Mark is the first to have them all.
Objectively, he's a can't-miss."

I'm not certain, but this candidate is as good as any as the origin of the "Mark Prior has perfect pitching mechanics" meme.

Mark Prior and Tom House

The problem with the article above is the first word of the last line in the quote above.


The word "objectively" implies that there is some independence between Tom House and Mark Prior, or at least Tom House's analysis of Mark Prior's pitching mechanics.

The problem is that that isn't the case.

As is clearly stated in first quoted line of the article, Tom House was Mark Prior's pitching coach and worked with him for years. As a result, Tom House clearly has some skin in the game, and some stake in Mark Prior's success, which makes him anything but an impartial, objective observer. If Tom House was to criticize Mark Prior's pitching mechanics, he would be criticizing himself and his methods.

Consequently, what else would you expect Tom House to say?

Of course, the fact that the article relies so heavily on the words of a clearly, and admittedly, non-objective analyst calls into question the wisdom of the entire article and whether it should ever have been published in the first case. Who uses as their primary mechanics analysis source someone who success is so closely tied to the success of the subject of the article?

That's very sloppy journalism.

Maybe with the word "objectively", Tom House was making the case that the computer, and not his beliefs, was telling him that Mark Prior was a can't miss prospect. However, anyone who works with computer models knows that they are highly dependent upon the assumptions that are built into them. In retrospect, it's obvious that the assumptions that were used to build Tom House's computer model were incomplete; they missed something important and that something quite possibly led to Mark Prior's problems.

Now, some will tell you that Tom House was correct all along and that Mark Prior had perfect pitching mechanics. They will tell you that Mark Prior's problems were caused by his collision with Marcus Giles or his poor conditioning and/or work ethic. However, I believe that if you compare Mark Prior's pitching mechanics to the pitching mechanics of Greg Maddux and Nolan Ryan, you will see some differences that in my opinion are very significant.

Tom House and Will Carroll

Some people point to the work of Will Carroll as backing up Tom House's claims about Mark Prior. See for example this quote in this article in Baseball Prospectus...

Rany Jazayerli: I'm not sure I understand why. Yes, he threw 126 pitches, and he's done that a lot this year, but I've been led to believe by multiple sources—as diverse as (Montreal Expos minor league pitching coordinator) Brent Strom and our own Will Carroll—that Prior's mechanics are as drop-dead perfect as they come. I'm inclined to think that Prior is the Tom Seaver of our generation, a pitcher capable of weathering high workloads because 1) he has great mechanics and 2) he's so effective that, even at eight innings a pop, he's unlikely to have to throw more than 130 pitches at a time.

There are also these passages from this article from by Will Carroll and Nate Silver and ...

In the terminology of pitching biomechanics, Mark Prior is a freak.

Stand near Prior in the Cubs' clubhouse, and you'll see that his calves are roughly the size of an average man's thigh. As Prior goes through his delivery and pushes off the rubber, the strong muscles drive his body forward. While the gyrations of a windup like Dontrelle Willis or Hideo Nomo make it difficult to assess their mechanics and add to the deception a hitter faces, Prior's efficient delivery disguises the linear driveline his pitches come through.

While we all know that the quickest path between two points is a straight line, few pitchers can regularly bring a baseball in a straight line to home plate.

Prior can.

According to Gary Heil of the National Pitching Alliance (sic), Prior was tested using high-tech Matrix-like technology to assess his mechanics.

"No one else was even close," Heil said. "He's the model; he's perfect."

Dr. Mike Marshall is a former Cy Young Award winner who has completed extensive scientific studies of the pitching motion. Using basic, Newtonian principles of inertia and reaction, Marshall's teachings show that Prior's controlled delivery is near ideal.

He'd be the Six Million Dollar Bionic Pitcher. Except that when his salary arbitration payday comes up, he'll undoubtedly make a lot more than that.

The problem is that Will Carroll also isn't totally objective when it comes to Mark Prior. Will Carroll and Tom House are apparently friends, and that friendship seems to have grown out of the writing of Saving The Pitcher. In Saving The Pitcher, Will Carroll talks at length about Tom House, Mark Prior, and Mark Prior's pitching mechanics. If Will Carroll were to criticize Mark Prior's pitching mechanics, he would be de facto criticizing the conclusion he drew in his own book, and that's something that authors tend not to do.

Tom House and Paul Nyman

I don't know for a fact where Mark Prior's pitching mechanics came from. However, given that Mark Prior's pitching mechanics so closely resemble the pitching mechanics of Anthony Reyes and Ian Kennedy, two other USC and Tom House products from the same era, that says to me that they were most likely taught to him rather than being totally natural. I do know for a fact that Paul Nyman has talked for a number of years about the idea of breaking the hands with the elbows and the Inverted W, and I would not be surprised if Tom House was influenced by the work of Paul Nyman and taught Mark Prior his arm action.

2009.3.12 UPDATE
I just came across a very interesting piece by Jeff Passan entitled Pristine Mechanics Caused Prior Pain that adds some more detail about who did what to Mark Prior and when. Some of the more interesting and relevant quotes are...

When he watched the gangly Prior as a sophomore in high school, (Tom) House saw the perfect specimen to build into the ultimate pitcher. For the next six years, he put Prior on a specific diet, ran blood work regularly, schooled him in mental acuity and, most important, imparted all of the lessons he had learned from high-speed-video and computer studies about proper mechanics to avoid injury.

“Because he was a computerized athlete,” House said, “he was supposed to be perfect.”

This helps to reinforce the idea that Tom House was heavily involved in the process of molding Mark Prior's mechanics and that Mark Prior likely didn't just come up with the Inverted W all on his own.

2010.6.30 UPDATE
It turns out that Mark Prior is making another attempt at a comeback, so I put together a piece that discusses Mark Prior's New Pitching Mechanics.

2015.3.3 UPDATE
I recently came across another piece in Baseball Prospectus Tom House Prospectus Q&A 2004 that firmly establishes the link between Tom House, Mark Prior, and Anthony Reyes.

For Further Reading

I have put together a number of pieces that address the topic of Mark Prior's pitching mechanics and the Inverted W...

   - Mark Prior's Pitching Mechanics
   - Mark Prior: A Different Perspective
   - Mark Prior's New Pitching Mechanics
   - Death to the Inverted W
   - The Inverted W: The Scentific Basis
   - Comments on Paul Nyman's Defense of the Inverted W

About The Author

Chris O'Leary never played baseball beyond grade school due to a shoulder injury suffered due to poor pitching mechanics. As a result, he is focused on ensuring that what happened to him doesn't happen to anybody else. The Epidemic is one way he hopes to achieve that goal.

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