Monday, December 14, 2009


I am a bit surprised that so many other people were surprised that the Brewers tendered a contract to David Bush next season.  Certainly his 5-9, 6.34 record was very unimpressive, but if you look a bit deeper you'll find a pitcher who was not nearly as bad as that record would indicate.

Studies have found that BABIP (batting average on balls in play) tends to be very consistent from pitcher to pitcher and team to team.  In other words, when you take away the walks, strikeouts and home runs, pitchers have very little ability to control whether a batted ball will turn into an out or a hit.  The Major League BABIP tends to be around .300 and was .303 last season.  Twenty-three of the thirty teams finished with BABIP within .010 of the league average.  The Brewers team BABIP was .305 - right about average.

There is no measurable ability by individual pitchers to maintain either high or low BABIPs over a number of seasons.  When a pitcher's BABIP is very different from .300, the difference can be mostly attributable to luck - good or bad depending on the direction of the difference.  In 2009, David Bush's BABIP was .320, but was .420 in the second half when he was battling back from an injury.

Another statistic that tends to be fairly consistent from pitcher to pitcher is "strand rate" - or the percentage of base runners allowed who do not score.  The league average is about 75%.  In the second half of last year, Bush's strand rate was only 50%.  Not only were more batted balls off of Bush getting through for hits, but they were doing so in bunches causing his ERA to be much higher than what it should have been given some better luck.

Luck tends to even out over time.  Just because Bush suffered from some incredibly bad luck last year does not mean that he will have good luck in 2010, but it means that the odds are with him in terms of it not being as bad.  Until two starts before hitting the DL, Bush was 3-3 with a 4.58 ERA.  His walk, strikeout and home runs percentages were very near his career norms.  With a shallow starting rotation, at only 30 years old, David Bush is not a pitcher the Brewers should be throwing on the scrap heap.

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