Recently I’ve been playing around with Baseball-Reference’s similarity scores, a tool designed to compare baseball players to other players with similar careers. I used the stat to try to forecast the next couple of seasons for some key Yankees. Somehow, amazingly, I forgot the single most important key Yankee: A.J. Burnett.
As much as it pains me to write it (full disclosure: I’m a Burnett fan, although I can’t explain why), A.J. remains the single most important Yankee in any given season or postseason. Until the Yankees get a rotation of five reliable starters, with Burnett serving as the sixth man, his status as the least-predictable member of the rotation makes him critical to the team’s success. The 2009 Yankees won the World Series with only three pitchers. If Andy Pettitte retires but Burnett has a solid season then the 2011 Yankees will have only three pitchers, an excellent offense, and serious title chances. If Pettitte retires but Burnett continues his decline, then the Bombers have only two pitchers, and problems to fill. A.J. is the X-factor precisely because the team can’t count on him. I have no idea why I didn’t use the similarity score to forecast his 2011 earlier. Fortunately, I’m doing it now.
For those who don’t know, Baseball-Reference provides three similarity scores for a given player: 1) Players who have had similar career totals. 2) Players who have had similar career totals, not for their entire careers, but up to the current age of the active player (33, in A.J.’s case). 3) Players who had similar careers through any given age (A.J.’s age 24 season, or his age 29 season). The second stat is the primary driver of this analysis. A score of 1000 is a perfect match. Higher is better. Anything over 950 is a close match.
Along with Jayson Werth, Mark Teixeira and Cliff Lee — all players I analyzed earlier — Baseball Reference doesn’t consider Burnett to be all that unique. All 10 of the players he is most similar to, through the age of 33, have scores of 930 or higher. Pete Harnisch rates as the most similar through age 33, with a score of 967, one of the highest I’ve ever seen. Ken Hill, Steve Stone, Randy Wolf and Chan Ho Park round out the top five. Each has a similarity score of at least 940.
Let’s hope that Baseball-Reference is wrong, and that A.J. is not similar to Harnisch. Their numbers certainly look similar, right down to being unpredictable season-to-season, but Harnisch was D-O-N-E in his age 34 season. He posted an ERA+ of 73 and never pitched again.
Ken Hill‘s career had almost the same trajectory. He posted an ERA+ of 102 in his age 33 season. In his age 34 season, however, his numbers fell off a cliff. He managed only 81.2 innings of 71 ERA+ pitching. He saw the major leagues in his age 35 season, a whopping 7.1 innings with the Tampa Bay Devil Rays in 2001, which counts as the big leagues by technicality more than anything else.
A trend is emerging with the players who were similar to A.J. Steve Stone is next on the list. I’ve never actually heard of this guy, but a glance at his numbers suggest that he was a slightly below average, often injured pitcher, who posted some excellent seasons in an otherwise unremarkable career. He was also toast after his age 33 season. That year he pitched only 62.2 innings of 79 ERA+ baseball. He never pitched in the majors again.
A.J.’s contemporary Randy Wolf is next. Wolf and A.J. are shockingly similar. They’re the same age. They both have a spotty track record of injuries. They both regressed considerably in 2010 — their age 33 seasons.
Mr. Diarrhea himself, Chan Ho Park, is next. Given his awful stint in pinstripes last season, its easy to forget that once upon a time Park had a few good seasons as an MLB starter (albeit in the NL West). What did he have in common with Burnett? Both had ERA+’s between 80 and 85 in their age 33 seasons. Park is a few years older than A.J., and has yet to toss 100 innings since his age 33 season.
For those who are curious, Todd Stottlemyre is next on the list. He was pretty good his age 34 season — when he pitched. He managed only 101.1 innings that year before succumbing to injury. He never pitched close to that many innings again.
The Yankees need A.J. Burnett to be successful. If Andy Pettitte comes back, a potent Burnett gives the team four legitimate starters. If Pettitte does not come back then a potent Burnett gives them the minimum three starters the team will require to compete for a Championship. Unfortunately, the numbers do not suggest Burnett has it in him. The annals of baseball are littered with injury-prone, erratic starters. There is an abundance of pitchers whose careers look similar to Burnett’s throu
gh age 33. Not a one of them was effective in his age 34 season. It is entirely possible that Burnett will bounce back to being a respectable big league starter in 2011, but he’ll be defying history if that happens.