October 15, 2010

Playoff Prospectus

Friday ALCS Pitching Matchup

by Matt Swartz

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Yankees at Rangers
CC Sabathia: 3.18 ERA, 3.75 SIERA
Sabathia struggled to throw strikes in his start in Game One of the ALDS, but the Yankees’ bats bailed him out and won the game anyway. As noted in last week’s summary re-printed below, Sabathia’s walk rate had increased in recent years, threatening his ability to be as economical with his pitches. As evidence he threw 111 pitches in six innings last week. Even still, Sabathia is back in to start Game One in Texas.

Sabathia put up a 3.25 SIERA in 2007 and 3.05 in 2008, but has fallen slightly to 3.70 and 3.75 in his first two years with the Yankees. His walk rate has increased from 3.8 percent in 2007 to 5.8 percent in 2008 to 7.1 in percent in 2009, and finally to 7.6 percent in 2010. Meanwhile, his strikeout rate has fallen to 20.3 percent this year, down from a high point of 24.5 percent in 2008. Some of this is the competition—the hitters that he faces in the AL East are much better on average than the hitters he faced in the AL Central or NL Central. The rest is quite possibly Sabathia regressing to the mean. Now, Sabathia’s 3.75 SIERA is still great, especially for the AL East, and he does have a tendency to beat his SIERA—this is his third year in a row of doing so by at least 0.33 points. While he is not the best pitcher in the playoffs this year, his endurance and ability to pitch three games in a seven-game series may be enough to help him get more batters out than other pitchers with lower SIERAs.

C.J. Wilson: 3.35 ERA, 4.18 SIERA
Wilson pitched six shutout innings in Game Two of the ALDS against the Rays, striking out seven hitters and walking only two. He only gave up two hits on 15 balls in play, despite allowing five line drives, because all five were caught by outfielders. This was the story of Wilson’s 2010 season—good fortune on balls in play. The Rangers got two wins out of Cliff Lee in the ALDS, and Wilson provided the only other one that they needed. Lee will again get two games in this series, and Wilson will attempt to provide the Rangers with one of the two other wins the needed from the rest of staff for Texas to win its first American League pennant.

 Wilson appeared to transition from relieving to starting relatively well this season, though his strikeout rate actually fell by 30 percent, which is more than the approximately 17 percent that the average pitcher sees when going from the bullpen to rotation (according to Tom Tango’s oft-cited “Rule of 17”). Wilson’s walk rate in 2010 was 11.0 percent, just a little bit higher than last year’s 9.9, explaining why his SIERA was so high despite his still solid 20.0 percent strikeout rate. However, Wilson allowed only a .267 BABIP and 6.1 percent home runs per outfield fly ball, masking some of the difficulties that he had in his transition. Wilson is definitely good at getting left-handed hitters out, but his .204 BABIP against them in 2010 led to a .144/.224/.176 slash line that exaggerates his skill level. Even so, his 3.8 K/BB ratio against them is certainly elite.

Matt Swartz is an author of Baseball Prospectus. 
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