We’re revving up for the postseason that starts today, where pitching matchups are sure to be highlighted. I’ll be discussing the difference between ERAs and SIERAs of pitchers in October games, and some of the reasons for those discrepancies. My goal is to be more detailed than simply looking at BABIP and declaring a pitcher lucky or unlucky, instead really getting at what the pitcher does to get hitters out and whether his SIERA is more indicative of his skill level than his ERA. If nothing else, we can gain a solid understanding of where pitchers excel and where they struggle, and how it will all affect the games.

Rays vs. Rangers
David Price: 2.72 ERA, 3.82 SIERA
Price is a great young pitcher with a great future ahead of him, but he is not this good yet. Some of the difference between his ERA and his SIERA is a result of strong defense and a big park. His BABIP is .272, but the Rays’ overall BABIP is actually a formidable .280, and a pitcher with his velocity certainly could best that mark without luck playing a role. His 8.6 percent home-run-per-fly-ball rate is bound to increase, though not quite as much as one might expect given that he plays in Tropicana Field. Price does strike out 21.8 percent of hitters, a very solid number for a starter, but also walks 9.2 percent. Pitchers who issue free passes to that many hitters eventually allow some to score. However, Price allowed only a .233 BABIP with runners in scoring position, the main reason why his ERA is so low. Chances are that Price is not going to be the best pitcher in the AL playoffs, but he is a solid mid-level ace who will keep the Rays in games.

Cliff Lee: 3.18 ERA, 3.03 SIERA
Lee actually improved his strikeout rate in 2010, increasing it from 18.7 to 22.0 percent, while dropping his walk rate from 4.4 to a microscopic 2.1. Lee's batted-ball rates were average yet again, but he was able to keep runs off the board thanks to his incredible walk rate. The key with Lee is getting hits because he is not going to let you on base on his own, as he walked only 18 hitters all year. Although Lee struggled with back problems later in the season, he is a pitcher who can completely dominate if healthy. For the Rangers, who are significant underdogs in any American League series, having a pitcher like Lee who can dominate a game twice each series is exactly how they can pull off some upsets.

Phillies vs. Reds
Roy Halladay: 2.44 ERA, 2.93 SIERA
Halladay leads the major leagues with a 2.93 SIERA, though his 2.44 ERA is even below that mark. No pitcher other than Lee walked fewer batters than Halladay, who only walked 3.0 percent. Halladay also struck out 22 percent of hitters he faced, and kept 53 percent of all balls in play on the ground. Doc led the league in outs recorded (three times innings pitched). With only 3.59 pitches per hitter, He was able to average 7.6 innings pitched per start. With a Phillies bullpen that is among the weakest in the playoffs outside of closer Brad Lidge and setup man Ryan Madson, getting two of their five NLDS games pitched by a guy that made it through at least seven innings in all but five of his 33 starts is a major advantage.

Edinson Volquez: 4.31 ERA, 3.68 SIERA
Volquez came back from Tommy John surgery strong, striking out 24.4 percent of the 275 hitters he faced, up from 21.6 in 2009 and similar to his 24.8 percent strikeout rate of 2008. Volquez’s swinging-strike rate jumped from 11.0 percent in 2008 and 10.0 in 2009 to 13.0 percent in 2010, despite the similar strikeout rate. He remains wild, walking 12.7 percent of hitters, above his 11 percent number in 2008, but below his 14.7 percent of 2009. What is quite different about the 2010 version of Volquez is his ground ball rate went up from about 47 percent in 2008 and 2009 to 57 percent in 2010. This included only 170 balls in play, but it is definitely a spike worth noting and should be worth checking if he can induce worm-beaters out of the bats of Phillies hitters. Volquez and Travis Wood are probably the best starters on the Reds, and although Wood appears to be relegated to the bullpen despite a lefty-heavy Phillies lineup, Volquez’s ability to dominate gives the Reds a fair shot in Games One and Four against Halladay.

Twins vs. Yankees
Francisco Liriano: 3.62 ERA, 3.02 SIERA
There are pitchers who can dominate with strikeout rates like Liriano’s 24.9 percent, and pitchers who can dominate with ground ball rates like Liriano’s 56 percent. Many people might think that this pitching matchup is a bad one for the Twins, but the better pitcher definitely may not be wearing pinstripes. Liriano was third in the majors in SIERA, falling just short of Halladay's 2.93 and Jered Weaver’s 2.97. His ERA belies his true skill level, as Liriano allowed a .335 BABIP in 2010, despite a relatively low line-drive rate of 17.3 percent. Liriano actually suppressed home runs per fly ball with just 7.8 percent of outfield flies leaving the yard, but his .324 BABIP on outfield fly balls was more than double league average of .153. Given Liriano kept fly balls from being hit for home runs so successfully, it seems very unlikely that he is particularly prone to hits on fly balls in general. Thus, it seems very likely that Liriano’s 3.02 SIERA is more indicative of his run prevention skill level going forward. Liriano only averaged 6.18 innings per start in 2010, making him beatable in a way that CC Sabathia is not, but scoring runs off of Liriano is tough to do. The Yankees will need to be their patient selves to get through to Liriano—it will be tough to make contact against him, and it will be even tougher to make good contact.

CC Sabathia: 3.18 ERA, 3.75 SIERA

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, 5.8 percent in 2008, 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.

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patient selves? i'm looking forward to jeter grounding out to 2nd on the 1st pitch.
I look forward to that too, but Matt is right: they're better off being their patient selves than they are being their impatient selves.