Basement Dwellers: What’s wrong with Bronson Arroyo?

NOTHING! He has one bad start out of every six or seven which screws up his ERA! Bronson Arroyo is the solution to all the Yankees’ proble…(sudden dismissive hand wave - Diet Coke ascites retention alert)

What I’m seeing here is a steady decline in his k/9 rates from mid-last season until now. His k/9 rate this year is its lowest since 2005 when with the Red Sox, and to me is looking pretty scary. I’ve long believed that Bronson’s bellweather stat is his strikeout rate, so color me concerned.

I’m no scout, so I can’t give you a precise cause. But let’s play a bit: his fastball run value has taken a huge hit this year, and appears to be where the problem lies among his major pitches from the pitch value data. But his fastball velocity, as he said, is essentially unchanged vs last year. And his fastball pitchf/x movement looks similar (maybe a slight drop in vertical movement, but not as large as 2007 vs 2008). Run values on his curve ball and change are actually improved this year, and are mostly unchanged on his slider, so those pitches look fine.

His walk rate is up this year. So, here’s a hypothesis: Arroyo’s not spotting his fastball this season, and so he can’t use it to properly set up his breaking slop as he usually does. And he’s behind in the count more than usual, causing him to give better pitches to hit. I can’t do my own pitchf/x at this point, but would someone like to test this who can assess strike zones? Maybe compare balls vs strikes on all 3-1 and 3-2 counts in 2009 vs. 2008 in which he threw a fastball? I’ve gone as far as I can go.