One of the keys to the Yankees’ success this year will be the performance of Shawn Chacon, who makes his first start of the year tonight against the Angels. Much has been made out of the fact that Chacon’s fantastic performance after being acquired by the Yankees last July was largely the result of an abnormally low opponents’ batting average on balls in play (BABIP). BABIP is generally considered something beyond a pitchers control. League average generally falls around .300 and pitchers whose BABIPs vary greatly from that norm in a given year can generally be expected to regress toward the mean in the following year. As a Yankee last year, Chacon posted a .240 BABIP, thus the pessimism many have about his chances for success in 2006.

However, Marc Normandin of Beyond the Boxscore writes in Baseball Prospectus’s latest Yankee Notebook that Chacon actually has a history of significantly low BABIPs relative to his home park. Thus, the improvement Chacon showed as a Yankee last year just might be a sustainable result of escaping Coors Field, a park that generally inflates BABIP, because Chacon just might be the rare non-knuckleballer who can consistantly supress his opponents success on balls in play.

The Normandin’s credit, this is something he noticed before Chacon threw his first pitch for the Yankees. That is significant not only as a testament to Normandin’s skills as an analyst, but because it proves his BABIP analysis isn’t simply a case of retrofiting the stats to explain past performance, but the detection of a trend significant enough that he was able to anticipate and extremely surprising improvement in performance.

Here’s what Normandin wrote around the time of the trade:

Shawn Chacon of all people looks like he might have the ability to control hits on balls in play a little bit. Ignoring the .314 BABIP, where he was closing, Chacon’s BABIP’s for his major league career read .275, .261, .276, and .272. Consider again that Coors raises BABIP by simply existing [the average BABIP at Coors during Chacon’s stay there was north of .330 –CJC], and we have ourselves someone lowering the batting average of balls in play against him at an extreme rate consistently.

In his new piece at Baseball Prospectus, Normandin provides this chart:

Year	Chacon BABIP	Park BABIP	Diff.
2001 (COL)	.294	.338	-.044
2002 (COL)	.261	.325	-.064
2003 (COL)	.276	.318	-.042
2004 (COL)	.314	.340	-.026
2005 (COL)	.272	.336	-.064
2005 (NYY)	.240	.311	-.071

What’s apparent here is that Chacon’s BABIP relative to his home park with the Yankees last year was low even for him, but not so low that one can’t expect him to be a valuable starter for the Yanks this year. With that in mind Normandin takes on Chacon’s PECOTA projection:

PECOTA assumes that BABIP regresses . . . His weighted mean projection BABIP is .287, and he is expected to finish with an ERA of 5.04; PECOTA is normally conservative, but that seems well out of line with what Chacon could be capable of, free from Coors for an entire season. This is not to say that Chacon is going to replicate his 2.85 ERA, as even the best in the business have a difficult time with that sort of thing in consecutive seasons. Rather, it seems entirely possible that Chacon can best his 90th percentile projection for ERA without actually having the peripheral statistics that PECOTA expects him to. PECOTA projects a 3.94 ERA at his highest point, and that seems to stem from a much improved K/BB of 1.69 (saying “much improved” before such a low K/BB makes one stop and think for a moment [Chacon’s K/BB tends to hang out around 1.40 as it did this spring, though curiously it was actually lower during his time as a Yankee last year –CJC]). Chacon may be able to surpass his projection simply by invoking the powers of BABIP in 2006.

So what exactly happens to the balls put in play against Chacon? Normandin presents the following breakdown of Chacon’s 2005 season:

Team	BFP	K	BB	GB	OF	IF	LD	IF/F
COL	322	12%	14%	25%	26%	2%	17%	9%
NYY	330	12%	11%	34%	21%	8%	13%	28%

LD is Line Drive Percentage, and IF/F is Infield Fly to Flyball ratio. Looking at these figures by themselves, it is apparent that balls hit into play ended their journey in the infield more often than not. 34% of the batted-balls were groundballs. The 19% jump in IF/F is incredible; some of that has to do with a small sample size, but increasing it to a midpoint between the two figures is still excellent progress. The Hardball Times glossary (which is also the source of these statistics) suggests that inducing infield flies may be a repeatable skill; if Chacon is adept at inducing infield flies, and can keep his G/F ratio from his days as a Yankee intact (1.14 as opposed to 0.89 in Colorado), New York might have themselves something here, and we might have the beginnings of an explanation as to why Chacon was successful BABIP-wise in comparison to other pitchers at Coors. Chacon’s previous work (excluding his year as a closer that just insists on messing with all of the data) matches up well with the figures above, so it does not seem like he was in any more of a groove in 2005 than in previous years, besides the normal success that comes with growth as a pitcher.

Normandin finishes his piece by cautioning that the jury is still out as to just how sustainable Chacon’s success might be, but it seems that the unshakeable optimism I have for his 2006 season just might be justified.