I think it is pretty common knowledge at this point, that in large part the Tigers pitchers results exceeded their performance last year. If you subscribe to the DiPS theory, that pitchers have limited ability to control whether balls in play turn into hits, then in general the Tigers pitchers got by without striking out a lot of guys because the defense was so good behind them. Part of me wondered it the pitchers still deserved some of the credit. That perhaps they were allowing more “fieldable” balls, thus having better defense behind them.
Well David Pinto at Baseball Musings has answered the question.
Using the probabilistic model of range, which looks at a number of factors (type of hit, direction of hit, hardness of hit, handedness of batter/pitcher) calculates the likelihood that a ball in play with each of those parameters is converted to an out. The summary table below is just for the Tigers starters and contrasts the predicted rate of turning balls into outs (DER is defensive efficiency ration, or the percentage of balls in play converted to outs), and the actual rate.
It’s pretty easy to see that Kenny Rogers, Justin Verlander, and Nate Robertson all benefited from some extra defense – or perhaps extra luck. Kenny Rogers had 18 more balls converted to outs than expected, which is another reason to expect that he might not be as good this year. It wouldn’t necessarily be because he’s older, or even unlucky – simply that he’s not as lucky.
If you look at the last name on the list, Jeremy Bonderman, he got the least help from his defense. Bonderman already has the great peripherals, and with a little better luck could easily shave off enough ERA to become a legitimate Cy Young contender.
On another note, David Pinto runs his blog as his job. He relies on ad income, and donations, for his livelihood. He always produces great analysis and makes the data available for everyone. I use it frequently on this site. Right now he’s running a pledge drive and asking for donations. If you enjoy this type of data, I’d encourage you to click through the link above and drop a little in the tip jar.