Site Search
Featured Reading
  • Starting Strength, 3rd edition
    Starting Strength, 3rd edition
    by Mark Rippetoe


Another post about Brandon McCarthy

If you're a betting man, you should know that the odds are good that this won't be my last article featuring the mechanics and health of the Texas Rangers starting pitcher Brandon McCarthy.

As my favorite subject, his mechanics have spent a lot of time on my computer monitor playing forward and backward, in slow motion, and in still shots. As a result, I have a small tendency to see a little bit of McCarthy in just about every pitcher. Every once in a while I run into a pitcher whose mechanics have a lot in common with him.

Meet University of Texas at Dallas junior Marvin Prestridge.

In light of recent mechanical changes, Prestridge doesn't look much like McCarthy does these days [Edit: this may not actually be true since I haven't seen high-speed video of McCarthy's new mechanics], but when I pulled up the video I shot of McCarthy last spring, the similarities were striking. The angles aren't quite the same, so you may have to use a little imagination in places.

McCarthy (left) and Prestridge (right) at the top of their leg kicks.

They don't look too similar at the top of their leg kicks, but they appear to have a similar degree of reverse rotation (turning their backs to the plate). McCarthy is more compact, and Prestridge lifts his knee much higher.

McCarthy and Prestridge at hand-break.

At hand-break, their mechanics are starting to run together. McCarthy sits a little lower on his back leg. Prestridge breaks his hands much closer to his body.

McCarthy and Prestridge right before their forearms start to turn over.

Before foot plant, this is the frame where their elbows stop moving upward and backward (toward 1B), and their arms begin external rotation. You can clearly see McCarthy's inverted W and that Prestridge's arm is below shoulder level with an extended elbow. Both pitchers have their arms well behind their shoulders.

I much prefer Prestridge's method of picking up the baseball to McCarthy's method from last spring. As a part of the changes he has made to his mechanics over the past 9 months or so, McCarthy's current pick-up features a full arm swing that positions his pitching arm much like Prestridge's arm.

McCarthy and Prestridge at foot plant.

By the time they hit foot plant, there's only one evident difference between the two: Prestridge is pulling his glove arm back toward second base. McCarthy's glove arm is essentially dead weight, while Prestridge's arm helps create additional rotational force through his shoulders.

McCarthy and Prestridge at peak elbow height just before elbow extension.

Again, the only difference is the glove arm action and position, though it appears that Prestridge has a greater degree of trunk tilt toward 1B.

McCarthy and Prestridge at full arm extension just prior to release.

At this point, the pitchers are literally inches away from letting go of the baseball. Prestridge is able to reach a little more toward vertical, thanks to his 1B-side trunk tilt.

McCarthy and Prestridge after primary arm deceleration.

After release, the pitching arm continues internal rotation while the body tries to keep the arm from flying out of socket. This frame attempts to capture the moment where internal rotation stops.

What's clear in this frame is that McCarthy's arm continued to fly forward, winding up closer to his head than to his chest. Prestridge's arm, on the other hand, is still essentially at shoulder level. This is the most significant difference between the two deliveries.

With McCarthy's arm positioned like this, the head of his humerus is placed in an anatomically questionable position while his rotator cuff applies extreme compressive force at the glenohumeral joint, driving the humerus awkwardly into the scapula.

Prestridge's arm is in a more natural position at this point, and as a result, I do not view his mechanics as risky despite their on-the-surface similarity to McCarthy's old, problematic mechanics.

McCarthy and Prestridge after complete deceleration of the arm.

McCarthy and Prestridge during the recovery stage after their follow-throughs.

You can follow Marvin Prestridge's season here: University of Texas at Dallas Baseball.

[Edit: For reference, here's a link to the video I shot of McCarthy at spring training in 2009.]


Please, don't buy this: ThrowMAX

I'd like to introduce you to the ThrowMAX, a device that aims to cure improper throwing mechanics by forcing the pitching arm to conform to a specific angle and motion. Two questions should immediately come to mind. Is the goal appropriate? Does the product accomplish its goal?

ThrowMAX on the right arm.After sifting through all of the marketing on their website (linked below) and ignoring their idea of good throwing mechanics to better focus on what the product actually does, one can find the pseudo-science used to justify the purchase and use of a ThrowMAX.

"Get your elbow up when you throw!!!" is the clear emphasis for this little contraption. According to the website, "the ThrowMAX alters the previous incorrect comfort zones of the throwing arm in order to take the stress off of the ligaments, elbow, growth plates, and shoulder." The device is supposed to force a pitcher to keep his elbow at or above his shoulder level and flexed to between 85 and 90 degrees.

We have now identified the product's goal: to take the stress off of the ligaments, elbow, growth plates, and shoulder by forcing the elbow to stay flexed between 85 and 90 degrees.

Is the goal appropriate?

It's really hard to argue with taking stress off of ligaments. This should be a goal for every athletic brace.

Taking stress away from the elbow and the shoulder are also admirable ideals. You can change how the stress is distributed across the two joints to place more stress on musculature rather than ligaments and bone. You can even limit stress by shortening the levers (i.e. bending your elbow to shorten the lever - the pitching arm - that extends from the shoulder).

Growth plates are an entirely different matter. The key growth plates in the pitching arm are on the humerus, and without getting too technical, you simply can not avoid applying stress to them. The only way to prevent growth plate injuries is to limit the number of high intensity pitches thrown by pitchers with immature growth plates.

Does the product accomplish its goal?

You can probably tell by the title of this post that the answer is a resounding, "No." The biggest and most obvious problem with this product is that elbow flexion has nothing to do with the position of the shoulder (glenohumeral) joint. Go ahead and bend your elbow to near 90 degrees. See how many different positions you can put your arm in - above your shoulder, below your shoulder, in front of your body, behind your body, and so on. As long as your elbow is flexed between 85 and 90 degrees, the ThrowMAX will tell you that you are throwing correctly no matter how high or low your elbow actually is.

There's also a key scientific fact missed in their discussion of how valgus stress ruins elbows. That fact is that valgus stress is at its peak when the elbow is flexed near 90 degrees1. This directly refutes their claim that the ThrowMAX reduces valgus stress. [This study and the physics that add to it are discussed in my article - Biomechanics: Ulnar Collateral Ligament.]

One thing that actually is accomplished is the shortening of the pitching arm lever which reduces horizontal flexion torque at the shoulder (glenohumeral) joint and helps limit stress in the anterior capsule.

Here's a brief list of other interesting claims from their website:

[T]he brace actually shows how to throw a curve, riser, sinker without damaging arms. This is because on [sic] all of these "junk" throws still must use some type of proper arm slot.

[T]he weakest point in the arm is the elbow area... The shoulder is the second weakest area...

[O]nce players learn to throw correctly [sic] they learn to recognize a throw based off of arm slot, [sic] or rotation of the ball. Using these skills, players can learn to hit with more consistency because they will begin to accurately recognize what's being thrown.

Since the brace has the body go through the full-range of motions on every throw, coaches cannot arm the ball meaning they won't get tired and drop the elbow leading to pain.

To have a look at this questionable product for yourself, click here, but please, don't buy this.

Do you know of another stupid pitching product out there? Tell me about it.


  1. Morrey BF, An KN. Articular and ligamentous contributions to the stability of the elbow joint. Am J Sports Med. 1983; 11:315-9.

2009 Texas Rangers Win-Curve Revisited

Back in January, I stumbled my way through a brief study of the relationship between Texas Rangers wins and attendance. The end result was the following graph. The yellow dot on the graph marks the 2008 attendance level, and the red dot marks the 2008 win level.

2009 Attendance Prediction. For a full description, read the original article (link at top).The Texas Rangers won 87 games in 2009, and the 2009 attendance numbers for Major League Baseball were compiled by Maury Brown in early October.

The model I prepared says that 87 wins should be worth an average attendance of 27,958. According to the data gathered and prepared for the Brown article, the average attendance of Texas Rangers home games in 2009 was 27,641. A difference of only 317 attendees per game translates to an overshot of only +1.15%.

As much as I would like to pat myself on the back for this, I have to acknowledge the extreme amount of luck involved with the startling accuracy of my prediction.

My model came with a sizable standard error attached to it: 2,646 attendees per game. You don't need to be a statistician to recognize how large that is or the uncertainty that it projects. I addressed this briefly in the comments of the original article:

The line in the graph marks the raw estimate based on the information provided by the model. At any given point on the line, the standard error says that the attendance level could be 2,646 higher or lower than the line.

With the reason for the 2008 drop off in question, it is probably unreasonable to expect that attendance will simply rebound to the 2006 or 2007 level. For this reason, I expect that actual attendance will fall somewhere below the line but within 2,646 attendees per game.

The luck of this season will definitely narrow the standard error of the 2010 model. Look for the 2010 model some time in February as the new season approaches.

If you haven't read the original article (or if you're into economics and data modeling) and you have 10-15 minutes to kill, I suggest giving it a read: Texas Rangers Win-Curve Part I: Wins vs Attendance.


Kyle Boddy on overtraining

Over at, Kyle Boddy has just published an article on overtraining - Training: Overtraining, or "What I See in High Schools Every Day".

He mainly refers to high school athletes, but I can personally attest to this being a problem at higher levels including college and the professional ranks.

When I played in college, our first pitching coach was only 2-3 years removed from his days as a Minor League Baseball player. The head coach had him develop the off-season strength program for our pitchers (myself included). He went with what he knew and gave us what he had been given as a professional athlete.

What we wound up with was a 2-day cycle, repeated 3 times weekly. Monday through Saturday, we lifted heavy, and we lifted a ton. We were graciously given Sunday as our day to recover.

This is a perfect example of both overtraining and not respecting recovery. For more, read Boddy's article.


Some news and updates for Fall '09

It's been quite a while since my last post, but new stuff is on the horizon. The transition back to college life has been interesting, and I'm finally settling into a schedule that will allow me to update with better regularity.

Part of what has kept me from updating is my work on my PITCHf/x tool. It's still under construction, so you'll see holes and bugs in a couple of places. New stuff will be added to that whenever I can find time to work on it. I've got a lot left in the tank for this.

I have also been working with the UT Dallas baseball team as an assistant pitching coach. Fall workouts are now over, freeing up about 20 hours a week for me to write.

In addition to my work with the baseball team, I've started serious strength training for the first time in my life. That's not to say that I've never been on a strength program before, but those previous plans lacked proper programming and weren't designed with any expertise.

To take nothing for granted, I started at the bottom. Kyle Boddy, of, plugged Mark Rippetoe and Lon Kilgore's Starting Strength, and I dove right in. I made a few small alterations to the basic workout plan, and along with a few small dietary changes - added lots of milk and an extra meal consisting of 2 peanut butter sandwiches (jelly optional) - I've been pretty impressed with my results to this point.

This winter, I will also be looking into NSCA's CSCS (Certified Strength and Conditioning Specialist) certification. Hopefully, my brain can keep pace with my ambition.