The Curious Case of Edward Mujica

Edward Mujica has a bad case of Gopher-ball-itis in 2010, up to and including the decisive, mammoth shot he surrendered to Ike Davis on Tuesday in the eleventh.  Last year he gave up a home run about every 7 innings (14 in 93 2/3 innings pitched).  This year it's every four (8 in 29).  Is the 2010 trend a sign of worry?

For analysis like this, I find Fangraphs the best site to look at.  Comparing 2009 to 2010 we find:

• Mujica's K/9, BB/9, WHIP, and BABIP are all better this year than they were in 2009.  In some cases, significantly so (like BABIP is currently 100 points better, .213 from .316)
• He's throwing more ground balls (his GB/FB rate is up) and giving up fewer line drives (13.2% vice 17.2%0
• His velocities are about the same:
• Fastball averaging 92.4 (2010), 92.7 last year
• Slider averaging 82.1, 82.7 last year
• Split finger fastball averaging 87.5, 86.9 last year
• Hitters contact rates are virtually identical to what they were last year.  Hitters are swinging at more pitches out of the zone, and Mujica is getting more swinging strikes.

By those metrics, there really isn't an explanation.  The only thing I can find is he's throwing a lot more splitter this year (up about 15%) than last, and he's not throwing as many fastballs (down 9%) and sliders (down 5%).  I don't know if favoring the split has led to a higher HR rate (it doesn't make sense, because the split is evaluated as his best pitch right now) or not, but it's the only major change Mujica seems to have made in 2010.

All his metrics indicate he's pitching better, but he's getting hammered by the long ball.  Odd.