At first blush, Phillies starter Roy Oswalt appears to be enjoying yet another stellar season in 2011. The 33-year-old right-hander's 3.38 ERA might rank fourth in Philly's loaded rotation, but that's still well under the 3.94 average for NL starters this year.
Look closer, however, and you'll see some cracks in that narrative. Oswalt's fielding independent ERA is closer to four. He's striking out a career-low 5.3 batters per nine innings after whiffing 8.2 per nine frames last season. Oswalt isn't fooling many hitters this year, and the culprit is a combination of his fastball lacking zip and a decision to emphasize the changeup in place of his breaking stuff.
Oswalt has nearly cut in half his percentage of breaking balls thrown. He tossed a curveball or a slider 29 percent of the time in 2010, but just 15 percent in 2011. In place of the breaking stuff, Oswalt has increased his use of the sinker (26 to 34 percent) and changeup (15 to 21 percent). He's still throwing a fastball about three out of every 10 pitches.
The problem is, Oswalt's velocity is down and hitters are connecting on his changeup.
He threw his fastball at an average velocity of 92.6 MPH in 2010, but just 91 MPH in 2011. His sinker averaged 92.4 MPH last year, and 91.2 MPH this season. Oswalt is still trying to live in the upper portion of the zone with his fastball...
Oswalt's fastball frequency in 2011(left), compared to the league average (right)
...but hitters are making more contact on his heater:
Oswalt's Fastball contact rate in 2010 (left) and 2011 (right)
Oswalt got hitters to swing and miss at his fastball 24 percent last year. In 2011, his miss rate on the pitch is 17 percent. The big league average is around 15 percent.
Using a sinker more often this year has contributed to Oswalt's lower K rate, too. Sinkers tend to have a low miss rate (the MLB average is under 13 percent). Oswalt is still getting more misses than average with the pitch (16 percent), but that's down from about 20 percent in 2010.
Oswalt's main offspeed pitch this year has been the changeup. That offering is also getting put in play far more often this year:
Oswalt's changeup contact rate in 2010 (left) and 2011 (right)
Batters missed the changeup 22 percent in 2010, but less than 11 percent so far in 2011. The MLB average is 29 percent.
Perhaps Oswalt is still feeling the effects of the lower back injury that put him on the DL in late April. But the current version of Oswalt -- lacking a top gear on his fastball, throwing more sinkers and relying on a middling changeup -- resembles a league-average starter far more than the ace we have come to know over the past decade.