I was always a bit miffed that Roy Oswalt didn't get the credit he deserved early in his career. It didn't help any when Andy Pettitte and Roger Clemens came to town and garnered all the attention. Sure Pettitte and Clemens were good pitchers, but it's not like this team wasn't already good to begin with: Jeff Bagwell still had a good year left; Adam Everett was one of the best defenders in the league; Morgan Ensberg was defensively sound as well, but also had offensive potential; Lance Berkman was posting legendary numbers. This was a good team before those two came, it was a great team after despite what played out during the season, but I'm getting off track.
Prior to the 2006 season, Oswalt had posted a 142 ERA+ in 980.2 innings. In 2006 he posted a 150 ERA+ in 220.2 innings. He led the league in both ERA and strikeout to walk ratio (SO/BB). How did he accomplish that? Well let's take a look.
Not Pitch f/x data only goes back to 2007 so we can't dig into that, but we can look at some of his other pitching statistics.
According to FanGraphs pitch type he primarily used his fastball 68.4%, with an average speed of 92.7 MPH, and his curveball 15.3%, with an average speed of 72.8 MPH. That's what I always loved about Roy O, the 30 MPH difference in pitch speed must have driven hitters crazy.
His pitch values (which show how many runs above or below a pitch was worth), also on FanGraphs, highlights something surprising. Oswalts second best pitch wasn't his curveball, which was 3.6, it was his slider, which was 9.4. He threw his slider for 8.4% of the time, with an average speed of 83.7 MPH. He must of noticed it to because he increased his usage of the slider in 2007 to 11.4% and stayed in the double digits as far as usage until this year.
The unfortunate thing is that 9.4 rating on his slider was an aberration. In 2005 it was rated at 2.7; in 2007, the year he increased his usage, it was rated at -2.5. Still that's better than the -3 he posted with his curveball in 2007. Oswalt really thrived off his fastball which has been worth 130.9 runs over his career. His second best pitch though is his slider, 30.4, which has been better than his curveball, 18.7.