Rangers vs. Rays
Hunter’s ERA makes him appear to be an intimidating Game 4 matchup for the Rays as they try to even the series, but his SIERA demonstrates that he is quite beatable. Hunter struggles particularly with striking people out, his strikeout rate declined from 13.5 percent last year to 12.7 percent this year. His batted ball rates are decidedly average as well, with 39 percent ground balls in 2009 and 42 percent in 2010. His pop-up rate was 10.0 percent in 2009, but fell to league average of 7.5 percent in 2010. The reason for Hunter’s low ERA is his BABIP of just .257, even lower than his .277 in 2009. Some of that is the Rangers' overall defense is strong with a .283 team BABIP in 2010 and .289 in 2009. In any situation where a pitcher puts up two low BABIPs in a row, you need to snoop around for a cause even if the explanation could easily still be luck, and in Hunter’s case, luck remains the most plausible reason. While some pitchers do keep their BABIPs low, those pitchers typically dominate the strike zone or induce a lot of pop-ups and fly balls. This is not the case with Hunter who clearly does not have either of these skills in bulk. Hunter has gotten by with just a .196 BABIP on ground balls this year, and has reasonably low BABIPs on outfield fly balls and line drives too (.146 and .699). Chances are that this is luck that is unlikely to persist, and the Rays certainly have to be hoping his luck runs out quickly.
Davis was yet another beneficiary of the Rays’ fabulous defense. His .279 BABIP is almost exactly even with the Rays' team mark of .280. However, Davis was even luckier on home runs per fly ball. The Rays as a team allowed 12.9 percent home runs per fly ball and Davis allowed 13.0 percent. Davis is yet another Rays pitcher who allowed particularly few hits with men on base with a BABIP of .219 in those situations. This is the primary reason for his ERA being so far lower than his SIERA. While Davis still has a promising future, he is a below average one at this stage and he probably is not the ideal pitcher to keep the Rays’ season alive.
Giants vs. Braves
Sanchez’s ERA has been all over the place the last three years, but his SIERA has stayed in the same range, gradually falling from 3.92 in 2008 to 3.80 in 2009, and now to 3.70 in 2010. His walk and strikeout numbers are both extremely high, while his batted ball rates are pretty average across the board. Sanchez has struck out 25 percent of hitters he has faced in each of the last two seasons, while walking 12 percent, making him a pitcher who is bound to aggregate large pitch counts quickly. In fact, Sanchez has averaged 4.0 pitches per hitter in each of the last two years and thus only 5.8 innings per start in 2010 and 5.4 in 2009. The key for the Braves will be to drive his pitch count up, because he is tough to hit otherwise. Sanchez has been the beneficiary of lucky BABIP this year of just .255 overall, thanks to a .114 on outfield fly balls, well below the .179 league average, and he also has just a .667 BABIP on line drives, below the league average of .716. These have enabled him to accumulate more innings this season than last. As his luck normalizes, he can be chased after closer to five innings than six on average, and if the Braves are patient, they will have another chance to tally some runs against the Giants’ bullpen.
I covered Hudson in a lot of detail a couple weeks ago, but the key to remember is that Hudson is a ground ball machine. While Hudson’s xFIP was 3.87, his SIERA shows the added benefit of extra ground balls. In fact, Hudson had extraordinary success on balls in play in 2010. His .253 BABIP was among the best in the major leagues, but Hudson has a history of pitching ahead of his peripherals, even ahead of SIERA that credits him for his very high ground ball rate. The reality is that Hudson still is not good enough to pitch nearly a run below his SIERA, though. However, with Derek Lowe, he is another major ground ball wizard on the Braves staff that the Giants will need to take good swings against.
Phillies vs. Reds
In 2008, after Hamels finished the regular season with a 3.09 ERA and followed it with NLCS and World Series MVPs, every journalist had his story—the 24 year old was mature beyond his years, he was a perfectionist and a hard worker, he had fire in his belly, and he did not let things get to him. In 2009, after Hamels finished the regular season with a 4.32 ERA and followed with disappointing performances in the playoffs, every journalist had a new story—the 25 year old was immature, had let the pressure get to him, and had become complacent in his preparation. Of course, I wrote on multiple occasions how Hamels was the same pitcher. Not only did he match his strikeout rate, walk rate, and ground ball rate almost perfectly in 2008 and 2009, but he also was similar in an impossible other number of ways: his line drive rate, home run rate, rate of balls hit to the outfield, rate of batted balls pulled, rate of foul balls, swinging strikes, rate of striking out hitters with two strikes, rate of infield pop-ups, and so on. He was simply lucky in 2008 and very unlucky in 2009. In 2010, Hamels now has a 3.06 ERAand every journalist has a new story on how Hamels got his groove back—you know, stopped letting things get to him, matured, and started working harder. The reality is that Hamels is now a better pitcher in 2010 than he was in both 2008 and 2009. He has had some success with a cutter he has developed, but more importantly has added two mph to his fastball, making it harder for hitters to tell his superb changeup from his heater as both arrive at the plate sooner than they did when he was the toast of the town and the goat of the town. The result is that Hamels has increased his strikeout rate from 21 percent in 2008 and 2009 to almost 25 percent in 2010, while also increasing his ground ball rate from 44 to 47 percent. His SIERA of 3.19 is 10th among major league starters, and fifth among those in the playoffs, giving the Phillies three of the top six SIERAs in the postseason.
Cueto improved his ERA from 4.41 in 2009 to 3.64 in 2010 thanks to an improvement in his home run rate. He allowed 1.26 home runs per nine innings in 2009 but only 0.92 in 2010. However, his ground ball rate went up only from 43 to 44 percent. The difference was that 15.2 percent of his outfield flies sailed over the fences in 2009, while only 11.6 percent did in 2010. The league average is around 12.3 percent, though in Great American Ball Park, you would expect that rate to be higher. Although some pitchers keep home runs per fly ball down more reliably than others, those pitchers tend to induce a lot of infield pop-ups. This did not change for Cueto, who gave up 7.1 percent pop-ups in 2010 after giving up 8.1 in 2009, indicating he is probably not as good as his ERA suggests.