Letting Others Do the Work

I got on the subject of looking up pitchers whose ERAs wildly differ from their actual performance level today so I decided to share. We hopefully all know by now that ERA is a very flawed measurement of a pitcher’s performance and that is why we defer to metrics like FIP, DERA or tRA. Using a combination of the three, I decided to pull the top five pitches on each side of the luck spectrum and present them.

First, a word of explanation on what I mean when I use the term luck. It actually comprises three distinct realms: defense, park and noise. A pitcher may change his or her approach depending on the quality of the defense behind him, though I am not sure if we have ever seen an extensive study really delve into the topic, but I consider the presence of a good or bad defense behind the pitcher to be outside of his control and thus, a pitcher is lucky if he has a good one and unlucky if he does not. Ditto on pitcher’s versus hitter’s parks. The last part is the actual luck, or noise as we statisticians are more apt to label it.

I will start with the “lucky” ones.

Kevin Millwood has seen his swinging strikes fall to a career low and he is throwing more pitches out of the zone than ever by a wide margin, dipping down below 50% for the first time all the way to 45.8%. His ground balls have returned to pre-2008 levels, but that has done nothing to help his home run rate, at its highest point as well.

John Lannan, the 24-year-old lefty seemed poised for a good season this year after some encouraging trends last year in his ability to throws strikes, miss bats and keep the ball on the ground. The strike throwing and the ground ball rate have at least remained stable, but the missed bats are down a whole two points and the home run rate remains elevated. Lannan is young and under team control for awhile, but I might consider moving him if I were the Nationals and could trick some team into giving up a haul of prospects for his shiny ERA.

Matt Cain has had his ups and downs in numerous key categories over the years to a point that he has become hard to peg down. This season has seen his strike throwing dip to a new career low while his first pitch strike percentage reaches a career high. The ground balls are up and the line drives are down. He is missing a touch fewer bats than last year, but he is right in line with his 2006-7 years. In fact, unlike the previous two pitches, Matt Cain has been legitimately good, he has just also been lucky.

Mark Buehrle follows the trend set above of pitchers missing the zone at career high rates this season. It builds off his 2008 season which was his previous career low in strikes thrown. Buehrle has gone from 52.5% to 49.7% and now to 46.4% over the last three seasons. That is a cause for concern.

Trevor Cahill completes the set with his lowest zone% of his career in 2009. Of course, that is somewhat cheating since Cahill has never before pitched in the Major Leagues. Or in Triple-A for that matter either, so we have no pitch data from which to compare against. Suffice to say that his .269 BABIP and pitching-friendly stadium are enough to land him fifth.

While this is a list of the five most lucky pitchers, which in and of itself, has nothing to do with their overall skill level, it is curious that all five of these have had just poor performances in the areas that do allow us a glimpse into their controlled performance level.