So Much Fun With Numbers

When your lab isn't set up yet at your new job, you end up with a lot of free time to spend messing around with Fangraphs and spreadsheets. (And what better way to look busy in the workplace than by messing around with spreadsheets?)

I've been giving most of my attention to the new pitch frequency information on Fangraphs, so for a change today I decided to dive headfirst into the velocity data. Specifically, the fastball velocity data. I'm going to go ahead and skip the long intro and get right to the numbers, since they're easy to understand and they're all you care about anyway.

note: minimum of 60 IP

Biggest MPH Increases Since 2005:

  1. Greinke, +4.7%
  2. Chacon, +4.3%
  3. Kim, +3.0%
  4. Heilman, +2.6%
  5. Hennessey, +2.1%
  6. Guerrier, +2.0%
  7. Tejeda, +2.0%
  8. Glover, +1.9%
  9. Pineiro, +1.5%
  10. Franklin, +1.4%

Biggest MPH Decreases Since 2005:

  1. Jennings, -4.0%
  2. Davis, -3.7%
  3. Zito, -3.2%
  4. Contreras, -3.0%
  5. L Hernandez, -2.8%
  6. D Wells, -2.7%
  7. Maroth, -2.6%
  8. Wakefield, -2.5%
  9. Fossum, -2.5%
  10. Wagner, -2.4%

We can learn a few things from this. For one, it's much easier to lose velocity than to gain it. Of the ten biggest increases, seven are the result of a move to the bullpen (which, as we've known for a while, allows you to throw harder). I don't know what changes Byung-Hyun Kim, Matt Guerrier, and Robinson Tejeda have made, but they stand as the exceptions. Generally speaking, you arrive in the big leagues throwing about as hard as you ever will in your life, and spend the rest of your career gradually losing speed. In this way, it's a lot like defense. You might take a step forward or two in the Majors, but it'll almost always be small.

For two, losing velocity is bad. Look at that list of the ten biggest decreases. That's not a list on which you want to find yourself. In 2005 those ten pitchers averaged an RA of 4.39. In 2007, it was up to 5.74. Every single one of them allowed more runs.

It's not just the top ten, either. In all, there were 15 pitchers with at least 60 innings in both 2005 and 2007 who had their fastball velocities drop by 2% or more. 14 of them saw their RA's balloon (Matt Morris, Jon Garland, Daniel Cabrera, and Roger Clemens are the other four, while Jeff Francis stands as the anomaly). That's pretty convincing. This isn't an exhaustive study by any means, but there would appear to be a strong correlation between losing velocity and getting hit around. Not that this is particularly shocking, but it's still nice to see.

Curious about what lost velocity might mean for the future, I isolated the 25 guys who had the biggest percent decreases between 2005 and 2006. I then took out the pitchers who moved from the bullpen into the rotation (Loe, Madson), which left me with a group of 23. These 23 pitchers lost an average of 2.0% of their fastball speed.

2005, Average:

IP: 178
Weighted RA: 4.49
Velocity: 89.6

2006, Average:

IP: 151
Weighted RA: 5.13
Velocity: 87.8 (down 2.0%)

2007, Average:

IP: 113.2
Weighted RA: 5.41
Velocity: 87.4 (down another 0.5%)

There wasn't a post-decline rebound. I don't know what I expected to find, but there you go. On average, the 23 pitchers continued to lose velocity, and where 20 of them were able to surpass 100 Major League innings in 2005, only 12 were able to do it in 2007. I'm not going to bother researching all 23 pitchers individually, but suffice to say that a drop in velocity one year bodes poorly for future effectiveness and playing time. A lot of this presumably has to do with injuries (injuries with velocity loss as an early symptom), but that's still useful information.

Bottom line: if you're a pitcher, you don't want the zip on your fastball to go away. While some people are able to survive, for most others it means you're probably either (A) already hurt, (B) going to get hurt, or (C) caught in a decline from which escape is nigh impossible. That's bad. You think the Giants are beginning to regret handing a blank check to Barry Zito? I don't know if I should curse Bill Bavasi for having tried so hard, or kiss him for giving up.

With all that in mind, I'll leave you with this.

Biggest MPH Decreases Between 2006 and 2007:

  1. Looper, -3.7% (moved to rotation)
  2. Sowers, -3.5%
  3. Schilling, -2.9% (already hurt)
  4. Wainwright, -2.2% (moved to rotation)
  5. Wright, -2.2%
  6. McCarthy, -2.1% (already hurt)
  7. Jenks, -2.0%
  8. Gorzelanny, -2.0%
  9. Contreras, -2.0%
  10. O Hernandez, -1.9%

Felix's fastball, by the way, got faster.

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