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June 23, 2006

Is Mark DeRosa For Real?

Had you told me in March that Mark DeRosa would be playing every day and batting fifth, I would have stuck a NAMBLA sticker on your car and drop-kicked your dog into the neighbor’s yard. I’m just that kind of guy.

Yet here it is, mid-June, and not only is DeRosa playing every day and batting fifth, he deserves to. With a line of .341/.399/.514, he trails only Gary Matthews (?!) in OPS among regular and semi-regular Ranger batters. He says he imitates Michael Young’s hitting style. Probably all of us could benefit from imitating Young.

Unfortunately for his long-term success, DeRosa has also been very lucky. A typical players bats just over .300 counting only balls hit into the field of play (that is, minus walks, strikeouts, and homers). Prior to 2006, DeRosa’s average in this respect was .295. This season, it’s .406. That can’t last.

I’m not arguing a DIPS-based theory that batters can’t influence their hit rates on balls in play. Unlike almost all pitchers, many batters appear to have (or lack) the ability to hit balls in play for a consistently high average. Ichiro!, Todd Helton and Bobby Abreu are examples. Overall batting average correlates moderately well to average on balls in play, though there are notable exceptions (Brad Wilkerson, Craig Wilson). Also, a high average on balls in play does not necessarily indicate a great hitter (Alex Sanchez, Willy Tavares).

Irrespective of the extent to which a batter can affect his average on balls in play, DeRosa’s .406 is not tenable. During 2003-2005, 476 batters attained the 501 plate appearances needed to qualify for the batting title. Here’s how they batted on balls in play:

Batters' Average on Balls in Play,
Best .401
Top 2% .363
Top 5% .352
Top 10% .342
Top 25% .327
Median .309
Worst .230

Ichiro! leads the pack with an average on balls in play of .401, achieved during 2004 when he batted .372 overall. Admirable though his improvement is, DeRosa’s no Ichiro. Even a 54-point drop in average on balls in play would place him among the top 5%.

Let’s say that DeRosa will bat .327 on balls in play for the rest of the season, equivalent to the top 25% among qualifying hitters. Also assume that his homer rate, walk rate, and rate of doubles per hit won’t change. How will he bat the rest of the season, assuming he plays in 80 of the team’s 89 remaining games at his current pace of 4.04 plate appearances per game?

Predicted remainder of season .279 .338 .430 .768 292 82 29 0 5 26 54
Actual games to date
TOTAL .303 .360 .462 .822 471 143 51 0 8 42 87

Under these assumptions, DeRosa would bat .279/.338/.430, well below his current pace but still far better than his pre-2006 career line of .263/.319/.380. However, a .768 OPS makes him a poor #5 hitter and a no longer an automatic play over Kevin Mench or Brad Wilkerson. The possibility exists that DeRosa will be permitted a lengthy occupation of the five-spot (or higher) while sliding into his usual lukewarm batting performance.

Posted by Lucas at June 23, 2006 05:47 PM