From SABR member Harry Pavlidis at Baseball Prospectus on April 2, 2013:
Two years ago Mike Fast (now with the Houston Astros) took a look at pitchers who gained or lost velocity between the end of 2010 and spring 2011. We won’t summarize his whole study here, but here’s the money quote:
There is definitely a predictive relationship between the fastball speed change observed in spring training and the fastball speed change observed in the regular season. Pitchers on average retained 41% of their spring training speed changes into the regular season, and the correlation coefficient for the sample here is r=0.53.
With that predictive relationship in mind, we’ve compared velocities from September 2012 and March 2013 and come up with some interesting results. This year’s study includes World Baseball Classic pitchers, who were all limited in their usage by rule.
First, a summary of gainers and losers.
Read the full article here: http://www.baseballprospectus.com/article.php?articleid=20058
Originally published: April 2, 2013. Last Updated: April 2, 2013.