The (Minor) Importance of Velocity Changes

Remember Jake Fox? Jake Fox was a catcher/third baseman/outfielder for the Cubs/A’s/Orioles/Pirates. He didn’t really shine at any defensive position, and his hitting really wasn’t any better. He cracked a wRC+ north of 100 for the first time in 2009 as a member of the Orioles, at 104. He, to this point, has a career 85 wRC+ and has been worth -0.9 WAR. If you are a follower of one of the above-mentioned teams, you may remember Jake Fox. If not, you shouldn’t. That is, you shouldn’t unless you are hiding a dirty little secret. The secret being that you have been paying attention to Spring Training stats. Because Jake Fox would rake in Spring Training. Like, pretty much every year. Observe:

Year OPS
2006 1.212
2007 1.61
2008 0.918
2009 1.033
2010 0.545
2011 1.122
2012 0.829

Jake Fox hit 10 home runs during Spring Training in 2011 alone. Save for his 2010 effort, he was the Barry Bonds of the Cactus and Grapefruit Leagues. But, of course, that success would never manage to transition to the regular season. This is why we give the caveat every year in regards to Spring Training stats. The sample size is too small. Many pitchers are working on new pitches or deliveries, or perfecting their ones they had before they took the winter off. We see guys in jerseys numbering into the 90s take the field seemingly every game. These aren’t real competitions, they are glorified practices. They are ways for batters to see live pitching, pitchers to see live hitting, and fielders to remember how to dive to their glove side or track a fly ball in the sun. It’s fun, it’s sunny, it’s a reminder that real baseball is about to boil over. But it is not important.

But as I browse Twitter and read articles about fantasy baseball advice (hey, I need all the help I can get), I see that people bring up one topic that we somehow all agreed circumvented the Spring Training argument — rose above it somehow; pitch velocity. So-and-so is sitting a full mile per hour higher than last year. What’s-his-face can’t throw as hard as he used to. So on and so forth. You may not care about it, but some people do care about it, and maybe they shouldn’t. Or they should.

When you write for a living, a semi-living, or for fun, you come to find words and phrases that you should just avoid. I cannot say the word “ostensibly” out loud. It never comes out right. I have a big problem with accept/except. I 100% know the difference, but my fingers have conspired against me and always type the wrong form. I either choose different words or grimace as I slowly plod the keystrokes with the fullest intent. I also cannot use the phrase “begs the question.” According to the rules of the thing, no one really knows how to use it, but I always catch myself using it improperly. So when I say that all this stuff about Jake Fox and Spring Training and velocity “begs the question” of whether pitch speed changes correlate to anything, it really doesn’t. It raises the question. Anyway, here are some answers.

A quick note about methodology — first off, I didn’t mine for Spring Training pitch velocities because that would be insane. I just used regular season numbers for this. Also, I characterized a starting pitcher as one who started 75% or more of the games he appeared in. This number is totally arbitrary. I then looked at the changes in (fastball-only) velocity between two adjacent years and grabbed the corresponding changes in some underlying, non-ERA numbers. I tried to adjust the graphs so that something a pitcher would consider positive, like a decrease in HR/FB rate, would point upward even if the actual number went down. Positive for the pitcher means “positive” on the graph. There are tabs for various stats and you can filter by role if you so choose. Capiche?

You’ve read over 650 words and consumed this big graph thing, so I feel that I can be honest with you — I didn’t think there would even be this much correlation. But, alas. The K% change makes sense. As does the HR/FB rate and the GB%. If a pitch is harder to catch up to, it might induce weaker contact. That doesn’t seem to jive with the LD% findings, though, but perhaps there are physical — like physics physical — things going on there.

There are certainly some outliers here, mostly due to playing time, but I didn’t want to crank the filters up too high as I wanted to make sure to poll a large group. Anomalies aside, I think this jives pretty well with what we may expect. Pitchers who can increase pitch speed have a better historical chance of improving their underlying stats. This isn’t always true, and it isn’t even mostly true. But it does happen, so maybe those fantasy articles aren’t totally nuts after all. Besides, I can’t imagine someone getting too excited about a pitcher’s velocity going down. There isn’t much intrigue in that. But there isn’t a whole bunch more in the latter, either. I’ll curb my enthusiasm for now. Call me when Jake Fox converts to a pitcher and can hump it up in the high 90s. That would grab my interest.

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David G. Temple is the Managing Editor of TechGraphs and a contributor to FanGraphs, NotGraphs and The Hardball Times. He hosts the award-eligible podcast Stealing Home. Dayn Perry once called him a "Bible Made of Lasers." Follow him on Twitter @davidgtemple.

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Like most things, it’s true but not some end all sign that a pitcher is done. Plenty of pitchers still do well when their velocity drops, plenty struggle a bit. Good read.


Put a fork in “lean” CC; he’s done.