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 2/3 innings, despite a mediocre 11:5 K:BB ratio. In 38 balls in play, only 13 have been on the ground and he has generated two infield popups. Yet, somehow Cain has kept runs off the board. The usually dominant Giants bullpen surrendered a lead in Game Two of the NLDS against the Braves, costing Cain a win, but he led a combined shutout of the Phillies in Game Three of the NLCS that gave them a series lead they did not surrender. The Rangers have the better lineup in this series, but Cain gives the Giants every reason to believe that their pitching staff can make up the difference.

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 1/3 innings against the Rays in the ALDS, Wilson struggled twice against the Yankees in the ALCS, allowing eight earned runs in 12 innings. He walked six and struck out six of the 53 hitters he faced, which is simply not good enough against a lineup like the Yankees. Wilson’s mediocre SIERA this season is a result of his average strikeout rate, and usually playoff teams can take advantage of pitches that they can get their bats on. The Giants do not have the strongest lineup that Wilson has faced this postseason, but they do have some power and if the lefty begins to surrender big hits, he could put the Rangers behind in a hurry.  

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Great preview. I've really enjoyed the pitching match-ups this postseason. (Probably because I'm a Giants' fan! Go Giants!)
Matt: These analyses are so densely packed with information it takes a while to absorb them. Thank you. My appreciation of each game has benefitted fropm them. You almost pin down what is so elusive about Cain- that is, with his tools, hopw the hell does he do it? Such sustained low BABIPs are a reeal outlier, unless his real skill is- he works to a low BABIP! I hope that in reading these pieces I can starting to grasp SIERA better, but it is still for me a complex concept. Thanks for your work.