I don’t think it will come as a surprise to anyone that I use FanGraphs a lot. It seems that every month, owner David Appelman rolls out some new shiny improvement to the site. Just recently, he gave users the ability to look up splits. But while everybody has been sorting and looking things up, something else has piqued my interest.
I’ve actually been meaning to look into this for a while, but it was the two articles Matthew Carruth posted on Monday that inspired me to finally do this. I want to look at the pitch speeds displayed on the FanGraphs player pages, which are provided by Baseball Info Solutions.
Over the course of this past season, I noticed a change in fastball velocity for a large number of pitchers. Though my evidence was anecdotal, there seemed to be a clear trend of increasing fastball velocity, at least from 2008 to 2009. I decided to look at all pitchers who threw at least 90 innings in a given year, and simply find the average velocity of every pitcher’s fastball. Why 90? Because I said so. The identities of the pitchers in the sample change from year to year, but I don’t think that changes much in this case. Here is the average fastball velocity for pitchers who fit the criteria:
2002: 89.47 mph
2003: 89.31 mph
2004: 89.67 mph
2005: 89.44 mph
2006: 89.88 mph
2007: 89.64 mph
2008: 90.13 mph
2009: 90.67 mph
That’s an increase of one full mile per hour in just two years. I don’t think that there’s some new wave of pitchers who suddenly started throwing really hard the last few years. More likely, it’s a problem with BIS’s data collection. From 2002 (the first year this data is available for) through 2007, the average fastball velocity remained between 89.31 mph and 89.88 mph, a difference of just .57 mph. Said differently, the average fastball velocity from 2002-2007 was 89.57. In just two years, that number increased to 90.67.
I looked at the same thing for other pitches, and there wasn’t much of anything to be found. Curveballs, changeups, and sliders didn’t show any clear trend like the fastballs did. This leads me to believe that it’s not a problem with the radar guns they’re using, or we’d see a similar trend across all pitches. I have another theory, however. It’s possible that pitch f/x data, which became available throughout the league in 2008, is influencing what BIS puts into its database. Maybe BIS saw that pitch f/x was reading pitches at faster speeds, and decided to “catch up.”
I don’t really have an answer for why this is happening, and I only half-believe my pitch f/x theory. If someone has an explanation for why this sudden change is happening, I’d love to hear it.