Pitchers and velocity loss, part one

The Hardball Times has a new pitching mechanics expert, Paul Nyman. He comes highly recommended from the previous expert, Carlos Gomez. Carlos, also known as ChadBradfordWannabee, is not working for the Arizona Diamondbacks.

The discussion on BTF was interesting. Poster JPWF13 says:

A LOT of pitchers see their raw velocity peak in their early 20s and then decline
Avery only appears different became came up so young and was effective at an early age, most guys whose fastballs peak when they are 22/23 we don't lose sleep over, because we never see them with a good fastball if/when they make the majors.

You see it all the time, prospect supposedly throws 95, 4 years later, in the show, he ocassionally reaches 92, and you think, "eh so much for the scouting reports".

Paul Responds, here is a part of it.

There is no physiological reason for someone to peak at 22 or 23. How do you rationalize the Nolan Ryan's, Randy Johnson's, or any other player who is under 30 throwing 95 mph. And let's not muddy the water by dragging steroid or HTH use into the discussion.

You really don't need to go into steroid/HGH use to explain them. Ryan and Johnson are freaks of nature, the outliers. The vast majority of hard throwing young pitchers do not keep their velocity past age 40 or anywhere near it. What I wonder is how likely is it that a pitcher loses velocity?

For the first study, I looked at Baseball America's 2003 Prospect Handbook. The usually give a range for a pitcher's fastball velocity, though in some cases I inferred one. For example, if all they say is "mid 90's" I'll count it as 93-96 or so. I compared the ranges to the velocity data from Fangraphs for 2007. I've got 54 pitchers that I wrote down from the book who pitched in 2007. For 39 of them, they are within 1 MPH of their 2002 range. Seems like Baseball America did a pretty accurate job, and prospects losing velocity is not as commonplace as I may have thought. 12 were under the 2002 range, and 3 were over. This is of course selective sampling, if we were able to put a radar gun on the prospects who did not pitch in the majors in 2007, we may very well come across many cases of injuries and reduced velocity.

The biggest drops were Brandon Webb, who threw 88 last year but 92-95 as a prospect. He seems to be doing OK though. Jose Contreras threw 90 last year, 94-96 in 2002. But then again, he was already over 60 year old back then. Noah Lowry was down to 87 from 91-92, and Joe Blanton was 89 after 93-97. I've used Blanton as a poster boy for not trusting velocity in scouting reports, but it turns out he's an exception and not the norm.

Three pitchers gained velocity in this time: JJ Putz, 95 after 88-91; Heath Bell, 95 after 89-92; and Andrew Brown, 95 after 89-93. All three were able to max out their throwing in short relief last year, Brown and Putz had been starters in the minors, though Bell was always a reliever.

Next project: Look at Fangraphs data to estimate aging curves for fastball velocity.