This week, I've been working on a piece for Beyond the Box Score about Joba Chamberlain's slider. As I was organizing pitch data by game, it was very noticeable that his velocity has fluctuated quite a bit over the past three years (yeah, like anybody ever talks about Joba Chamberlain's velocity ...). So, here are game averages for Joba's four-seamer and slider, going back to April 1st, 2008.
The first noticeable dip is near the end of 2008; that was following his shoulder injury in August. In 2009, when he was a starter, he was down about 3 mph on average from 2008 and usually sat at around 92 mph. In 2010, he gradually regained his velocity and was consistently in the mid-90s. (In case you were wondering, those outliers up at the top in 2010 are from some August games at Kauffman Stadium and U.S. Cellular field where the gun is hot.) It looks like he's more or less back to where he was in 2008; he threw harder in 2007, but there is limited data from that year and I'm skeptical of its accuracy.
I'll have another (much longer) post on Chamberlain up here tomorrow and on BtB Tuesday.