Thoughts on Jeff Passan’s Book, “The Arm”

I have finally finished Jeff Passan’s new book, “The Arm” and have a few pieces of information I found interesting.

• When the ulnar nerve is brought in injury discussion people get excited. Here is why, “… ulnar nerve, a tube of fibers that originates at the spine snakes down the arm and controls fine-motor movement in the hand.” The nerve may need to be moved to get away from bone chips.

Mike Marshall would even take it a step further

“… when a pitcher showed professional potential, he would go in for surgery to transpose the ulnar nerve.”

• The major issue with a second Tommy John surgery is the holes drilled in the arm weakening the bone like it has with Jarrod Parker. Here is a description when the book mentions Todd Coffey’s second surgery:

“Surgery dabbles in fractions of a millimeter. The drill holes from Coffey’s first surgery left his ulna in danger of cracking.”

• Also with Todd Coffey’s surgery, Neal ElAttrache states that the third party ligament used for Coffey will likely be a “little slower” to take hold in the arm. The point I took from this information is to find out if the ligament is the player’s or someone else’s which will take longer to heal.

• Theo Epstein mentioned “left-handed pitchers age better”. I love me some aging curves, so let me find out. Here are the FIP- and ERA- aging curves from 2002 to 2015.

I don’t see a big difference with the curves following each other pretty close. Just looking at the numbers from age 31 to 36 (Lester’s ages for the contract), the increase will be:

Stat(hand): Change
FIP-(right): +27
FIP-(Left): +27
ERA-(Right): +42
ERA-(Left): +44

The idea of left-handed pitchers aging better seems to me to be an old wives’ tale, something Epstein made up, or my data is wrong.

• As players come back from the surgery, they start throwing at increasing distances. It seems like this routine is done this way because it always has been done that way.

“The distances are entirely arbitrary, part of a program that exists more because that’s how it’s always been done and not because 45 feet or 135 feet or any distance in between makes particular sense. Because doctors and trainers still done know the ideal, every team’s program varies slightly.”

• As with about any book, I found myself with some additional reading.

I would recommend at least getting the highlights from these three articles by Dr. James H. Buffi on arm stabilization. He work was so groundbreaking, the Dodgers quickly hired him and his new work is no longer publicly available.

Additionally, “Arnie” states the follow:

“… the best article I ever read, on the stress and the percentile of stress that’s being put on the medial side of the elbow and the shoulder, being the deltoid and the biceps tendon are, and they said when a guy is throwing up to ninety-two to ninety-five mph, yet alone one hundred, the stress level that goes on the ligaments and tendons that grasp the rotator together, that grasp this elbow together, are key cogs in it.”

I have not been able to find this article, so if anyone could point it my direction that would be great.

A study by Wiemi Douoguih is mentioned which looked at 250 pitchers and if the dreaded inverted-W caused more pitcher injuries.

“Of the roughly one-third of the pitchers surveyed who threw with the Inverted W, 30 percent had arm surgeries. Of those with non-Inverted W deliveries, 27 percent underwent surgery. The difference was negligible.”

Douoguih did though find a “…significant difference in surgery rates among those with early [trunk] rotation.”

I am not a mechanical wizard, but the early trunk rotation means the arms are behind the trunk when the trunk begins to rotate.

• In this article mentioned in the book, Kyle Boddy predicts that gaining 4 mph on a pitcher’s fastball may add an additional win’s worth of seasonal pitcher production.

• And finally, some deep thoughts by Todd Coffey:

“I had to take a shit with my legs straight out,” Coffey said. “You ever tried to take a shit with both legs straight? Try it. And then try being able to wipe left-handed without being able to bend both knees. It was not fun. Shit everywhere. Literally.”





Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR twice, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.

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dtpollittMember since 2016
8 years ago

I thought this book was excellent. As a Cubs fan the chapter on Lester–and let’s be real, it is mostly about Theo–is superb behind-the-scenes. The investigation and analysis Passan provides regarding different cultural beliefs on arm treatment is very good. I highly recommend reading it.