Stats & Info: Matt Swartz

BP: Ubaldo's inevitable regression

June, 17, 2010
6/17/10
11:36
AM ET
Ubaldo Jimenez is a very talented pitcher. After all, the vast majority of the pitchers on the planet cannot throw 100 mph while mixing in a nasty changeup, curveball and slider. However, the Ubaldo Jimenez that has 12 wins a month before the All-Star break and carries a microscopic 1.16 ERA into his start for the Rockies against the Twins at Target Field this afternoon has not been very different than the regular front-of-the-rotation flamethrower that posted a 3.47 ERA while playing half his games in Coors Field last year.

Looking at SIERA is an excellent starting point to get a sense of how well someone is truly pitching. No metric can be the beginning and ending statement in a player’s performance, but SIERA does a very good job at determining how well pitchers are doing -- particularly those who help themselves with extreme ground balls, like Jimenez. Last year, Jimenez posted a 3.60 SIERA, good for 20th among major league starters. That is fantastic. The majority of pitchers with 3.60 ERAs in any given year are probably a bit lucky and see their ERAs go up the season while pitchers with 3.60 SIERAs tend to have ERAs that stay low. In Jimenez’s case, his ERA has plummeted. However, his SIERA has improved to just 16th among major league starters at 3.43. That is a slight improvement but it also indicates that Jimenez has been a very lucky pitcher. As it stands, his home run, strikeout and walk rates are virtually identical to what they were last year.

Sabermetrics has long backed off the claim that pitchers do not control their batting average on balls in play (BABIP), but what we have learned is that pitchers do not have very much control over it. Jimenez has a .235 BABIP, compared to the major league average of .298. There are great pitchers that are capable of dropping their BABIPs to .280 on a consistent basis, but none who can will weakly hit balls not to become bloop singles or 20-hop singles. And it is not possible for a pitcher to allow only hits on 23.5 percent of balls in play over a prolonged period of time. The pitchers that tend to hold their BABIPs down also do not play their games at Coors Field. Even with Colorado’s terrific defense, the rest of the Rockies pitchers have a .292 BABIP. Flamethrowers can certainly hold BABIP down a few extra points, but Jimenez has been fortunate to come in so far below his similar BABIP-preventing fastball wizards.

Breaking down Jimenez's BABIP, we see that his line drive rate is 17 percent, just below the 18 percent number he had in both 2007 and 2008. Pitchers have extremely little ability to control their line drive rate, even if they do have a little bit more control over the actual BABIP on line drives (though not much). Jimenez's BABIP on line drives is .600, well below the major league average of .722. This is just not sustainable, especially in Coors Field where line drives fall in more than in the average park.

It is tough to write an article predicting the fall of Jimenez, because the fall just is not going to be that bad. The 26-year-old Dominican is one of the 20 best pitchers in the major leagues, and could get better given his youth. There are very few pitchers who can strike batters out so easily, all while generating 55-56 percent ground balls, a feat Jimenez has accomplished three years in a row. Even if his 3.43 SIERA matches his ERA the rest of the way, he will still finish with an ERA around 2.60, and he’s a good bet to get 20 wins with 12 already in the bank. I think he wins the National League Cy Young award this season and is good enough to do it more than once in his career. However, most pitchers who win the Cy Young have some luck come their way, and Jimenez is no exception. In fact, he’s been fantastically lucky, which has finally drawn plenty of attention to the fact that he is a great pitcher. He is just not the best, at least not yet.

Matt Swartz is an author of Baseball Prospectus.

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