Matt Cain: 3.14 ERA, 3.90 SIERA
DIPS metrics like SIERA do not work well for Cain. They are bound to estimate skill level effectively for the vast majority of pitchers, but some will be the exception to the rule. However, one must be careful not to stick a feather in the cap of every rookie who beats his SIERA, and then not fall victim to confirmation bias for those who have a second year of beating their peripherals. There will be a handful of pitchers that are lucky two years in a row and appear to have SIERA-beating skills but really do not. However, it is now four years in a row with Cain. After posting a 4.15 ERA in 2006, just above his 4.03 SIERA, Cain has transformed into a pitcher that pitches ahead of his peripherals by quite a large margin. In 2007, he had a 3.65 ERA and a 4.20 SIERA; in 2008, he had a 3.76 ERA and a 4.23 SIERA; in 2009, he had a 2.89 ERA and a 4.09 SIERA; and in 2010, he had a 3.14 ERA and a 3.90 SIERA. None of these are bad SIERAs. Cain strikes out 20 percent of hitters and walks only 6.8 percent. He is by no means a ground-ball wizard, but he induces popups regularly (11.4 percent of balls in play in 2010) suppressing his BABIP. His BABIP in his career is .270 (with a .259 BABIP at home and .283 on the road), and his HR/OFB is just 9.6 percent. Chances are that Cain has been a little bit lucky in this string of SIERA-beating ERAs, if for no other reason than it seems almost impossible that he was unlucky. However, Cain is one of the better pitchers in the postseason and gives the Giants a solid one-two punch with Tim Lincecum to bring into the World Series. His playoff performance thus far has been masterful. Cain has not allowed an earned run in 13
C.J. Wilson: 3.35 ERA, 4.18 SIERA
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 rotation (according to Tom Tango’s oft-cited “Rule of 17”). Wilson’s walk rate in 2010 was 11.0 percent, just a little higher than last year’s 9.9 percent, explaining why his SIERA was so high despite his 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, though the Giants’ righty-heavy lineup negates some of this advantage. After a scoreless start in 6
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