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BPIP and the Rays

A lot of people have talked about the idea of slugging percentage and the variety of hits being infused into WHIP, with a few vague references and 30 years worth (~4,300 samples) of 100 inning throwing pitchers BPIP was finally ready to make a return.

First let me explain what exactly it is: Bases Per Inning Pitched. Creative, I know, essentially it takes the total bases allowed, adds in the bases granted on walks, and divides them by innings. From there we can compare the correlation between BPIP and WHIP to confirm the suspected: BPIP has a much higher correlation to ERA (.7957) compared to WHIP (.63) and even FIP (.58) although do take into account that I used substantially less data for those two statistics. With the regression and equation, both listed on the chart below, we can plug the BPIP number in for a pitcher and get a projected ERA that, in theory, would be pretty close to the pitcher's actual ERA.


Now, let's actually use the projected ERA to see where the pitchers stand compared to their expected selves:


I'd like to focus initially on the rotation's results. Impressively each of our pitcher's has a pERA under 5. Scott Kazmir and James Shields have been really, really good. Edwin Jackson and Matt Garza have avoided the hit bug, despite some pesky walks, and Andrew Sonnanstine has allowed far too many extra base hits this year, but he's still a useful number five innings eater.

For the first time in franchise history the Rays actually have five pitchers who range from great to above average to average. Even if progression and regression don't even out perfectly the Rays have the makings of a rotation that can seemingly compete.

Along those same lines how good has J.P. Howell been in the bullpen? His velocity is the highest of his major league career (85.7 compared to 2005's 85.4) giving some water to the idea that the bullpen really will add velocity. Howell has been death against lefties (.452 OPS) and righties (.601) while doing exceptionally well in high leverage situations (.390 OPS in 23 at-bats). I don't know the Rays plans for replacing Al Reyes next year, but Howell might slide into the 7th inning slot allowing for dual cannon double inning action when combined with Dan Wheeler.