Joe Mauer and Fastballs

Yesterday when I was looking at Joe Mauer’s numbers I noticed he sees a lot of fastballs. Generally the better the hitter the fewer the fastballs he sees, but Mauer, the second best hitter in baseball last year, saw more fastballs than anyone else in the top twenty. (Todd Helton, with the 21st best wOBA, is the player with the best wOBA who saw more fastballs than Mauer).

Part of this has to do with the fact that the true relationship is between power and fastballs seen. So it is not that good hitters see fewer fastballs, but that power hitters see fewer fastballs and good hitters are often power hitters. Dave Cameron showed us this relationship last year. Compared to other top hitters, Mauer is not as much of a power hitter, which explains, somewhat, why he sees more fastballs. Here is the relationship for 2009 with Mauer indicated with the filled circle.

He is not the farthest from the trend line, but pretty far, meaning he sees more fastballs than you expect for a hitter with his power. Part of this is because Mauer’s power is so new, and pitchers have not changed their strategy. But pitchers rapidly changed their pitch usage against Ben Zobrist, who busted out this year and saw just 53% fastballs after seeing over 64% every previous year.

The excess of fastballs to Mauer is particularly interesting because he was the second best fastball hitter in baseball in 2009 (only Albert Pujols was better) and 25 of his 28 HRs were off fastballs. (That is based on the pitchf/x pitch classifications. The BIS classifications backs this up, saying he hit 24 HRs off of fastballs).

My guess is next year Mauer will not see 60%+ fastballs like he has so far in his career. Do you think that will have any effect on his game? Head over and project his 2010 performance.