Imagine if you could tease out from a player's performance the skill-wheat from the luck-chaff and make a more nuanced prediction of his future results. The imagination is not so very boggled here; we have many tools in the sabermetric toolkit that help us do this. On the hitting side we have, first and foremost, BABIP, now so widespread in its use that it has its own Wikipedia entry.
Pitching performance is dependent on a larger array of variables, and so requires a more robust distillation. Seamheads around the world have been nose-to-the-grindstone on that, to the point that many of the rough edges (on pitching stats, not on noses) have been smoothed. There exist several calculations that are independent of defense, BABIP and other noise.
Last year, Baseball Prospectus put its SABR light ray to use on the obverse proposition: rather than strip out the obfuscations, why not focus on the core elements of a pitcher's work. Pitchers can control their their walks and strikeouts, their home runs allowed, and the ratio of ground balls to fly balls allowed, so why not simply measure those things to understand their core skill sets? After developing the statistic, called SIERA (skill-interactive ERA), they tested its predictive ability and found that it was indeed superior to other measuring tools.
In other words, if you see a pitcher who went 20-8, 2.97 last year, you probably assume he pitched spectacularly. In fact, what you're seeing is a pitcher with spectacular results. The correlation is imperfect. If that hurler benefited from great defense and run-scoring support, fabulous relief pitching, an unusually low BABIP, unsustainable success with runners in scoring position and a good home pitching park, you could conclude that fortune has smiled upon him and may be looking elsewhere next season -- what we commonly call regressing to the mean. Conversely, if he served up a lot of strikeouts, limited his walks and HBPs, and kept the ball in the park and on the ground, he's got the requisite core skills to repeat, rinse and shine.
As soon as SIERA was introduced last year, I thought how interesting it would be to examine the 2010 pitchers whose SIERAs varied dramatically from their actual ERAs and then observe their 2011 performances. BP has provided just that list, so I present to you the hurlers whose performance will be worth noting this year. (Of course, these predictive tools have enormous Fantasy Baseball value, and in fact, BP has become more of a Fantasy Baseball site.)
Just one note of caution: Judging a player on a single season can be like judging a city's climate by one day. The weather in Fargo might be nicer than in Miami on a given day, but not over the long haul. So seamheads ordinarily use a rolling three-year average when measuring player performance and BP is doing that with the gentlemen listed below.
The four unlucky moundsmen capable of dramatic rebounds in 2011 are Josh Beckett, Brandon Morrow, Aaron Harang and Dan Haren. Beckett, slowed to 128 innings by a balky back, went a miserable 6-6, 5.78 for the Red Sox. But SIERA saw his performance more generously and believes he's more like a 3.84 ERA starter, which is among the league's elite. If he's healthy, expect his ERA to be as well.
Morrow, a rookie for Toronto last year, shoves strikes down batters' throats for a sterling 3.15 SIERA. An out-of-kilter .344 BABIP pushed his ERA to 4.45, but the SIERA suggests he could be a star in 2011. Aaron Harang's SIERA of 4.44 was 88 points better than his actual ERA in Cincinnati in 2010. Now toiling in a pitching-compliant Petco Park in San Diego, his actual ERA could plummet. The same for Haren, who spent half of last year in Arizona's hitter-haven park.
The four sons of serendipity in 2010 who might be best avoided in your fantasy draft are Brian Duensing, RA Dickey, Livan Hernandez and John Garland. Hernandez is a walking cautionary tale. Knuckleballers like Dickey are often immune to the Laws of Sabermetrics, so he might not belong on this list. Garland is a flyball pitcher, but at Petco that wasn't a demerit. He's employed by the Dodgers this season and he'll lose baseballs if he keeps his pitches up. Duensing, who pitched half in relief and half in the rotation for the Twins, had a 2.62 ERA with 4.22 skills. His inability to miss bats may come back to haunt him.
Over the years, SIERA, like all baseball metrics, will be whittled and honed as more information is revealed and more smart people contribute to its improvement. It'll be interesting to see how well it identifies the outliers in its first year.
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