The Rays just played the Los Angeles at the end of July. They faced Haren, Wilson, and Greinke, and didn't do half bad, taking two out of three on the strength of back-to-back shutouts (not complete games) by Matt Moore and Jeremy Hellickson. Now, they'll essentially redo that series, adding Jered Weaver to the mix. With the Angels already falling off the pace, a Rays series win would go a long way toward knocking them out of the wild card hunt.
For a standard series preview and observations on Haren, Wilson, and Greinke, just go back to the preview from the last Angels series. For a breakdown of Jered Weaver and a bit of pontification on where I'd like to see ERA estimators evolve, read on.
First off, Weaver is a a bona fide FIP-beater. In his seven year major league career, he's only once not posted an ERA under his FIP. Also, every single year, he's posted a FIP better than his xFIP. How has he done this? Consistently low BABIP, and consistently low HR/FB. He's a fly ball pitcher, and as you might expect from a fly ball pitcher with a low career BABIP, he gets a ton of popups. In 2012, he's actually gotten fewer popups than he ever has before (still an above average 11.3%), but he's balanced that out with more ground balls than he's ever gotten before. And here's why I think SIERA miscasts him.
As any ace pitcher should, Weaver has a lower SIERA than he does xFIP. That's because SIERA sees a strikeout artist and assumes weak contact. But SIERA also assumes weak contact for pitchers who are either flyball or groundball machines. What happens when a flyball machine changes his pitch selection and improves on one pitch so as to get more ground balls, while leaving the rest of his offerings the same? SIERA only looks at the complete package, and sees a guy who is no longer as extreme in either the groundball or the flyball direction, so it thinks he's gotten worse. I'm not so sure that's the case.
Take a look at Weaver's repertoire.
None of Weaver's pitches are particularly fast. All three of his fastballs are in the upper 80s, his changeup and slider are right around 80, and his curve sits in the low 70s. What his fastballs do have is a wide range of horizontal movement and a ton of rise. The biggest change in 2012 is that Weaver is throwing his two-seamer more than he ever has before, and for the first time in his career, it's actually producing ground balls (30.1% career, 41% in 2012). His curve has always been a groundball pitch, but now it's become extreme (42% career, 52% in 2012). His other pitches still get the flyballs at their usual extreme rate.
So if Weaver is getting less extreme overall batted ball results because his different pitches balancing each other out as they move toward their respective extremes, are you comfortable concluding that he's no longer generating as weak of contact as he used to? I'm not. This is essentially what SIERA thinks of Weaver, though, and it's one of the reasons I would really like a SIERA-type metric that looks at individual pitch types.