Okay, let's get to the bottom of this super scientific statistical model developed by Harvard Ph.D. Shane Jensen that says Derek Jeter was the worst fielding shortstop in the majors between 2002 and 2005. Yeah, I know it's kinda like saying T. Boone Pickens is the poorest billionaire at the table when he's lunching with Warren Buffet and Bill Gates, but this is Jeter we're talking about, so we can't just let this stuff slide.
Dr. Jensen, an assistant professor of statistics at the University of Pennsylvania's Wharton School, has parsed the playing surface of a baseball field into a mosaic of squares 4 feet by 4 feet in dimension, evaluated the fielding of every ball put into play between 2002 and 2005, and run the data through his whiz-bang Spatial Aggregate Fielding Evaluation probability model (aka SAFE). Let's look inside the black box and see what makes SAFE tick.
The SAFE website lays it all out there for your reading pleasure. Take, for instance, the section on the methodology for "grounder balls in play." No, that's not a typo; that's what the good doctor calls it, which tells you something about his street cred. Now, fasten your seat belts:
We model the probability of a successful play on a grounder as a smooth function of the angle between fielder location and the BIP path. We model different functions for each velocity category, and also allow a different function for fielders moving to the left or the right. These models are calculated using the data from all infielders, and so represent the ability of an aggregate fielder at each position.
You got that? Neither do I.
But here's what I did get as I dug a little deeper. Jensen admits he has no idea where any of the fielders he evaluated were positioned on the nearly half a million plays he number-crunched. Nope, instead he assumed they were all stationed "where each position has the highest overall probability of making a successful play." Now there's some airtight science for you.
I'm guessing those of you who know a ground ball from a grounder ball consider this little bit of wishful thinking to be just a tad important in evaluating fielding skill. And wait! It gets better. While Jensen claims Derek Jeter, he of the Gold Glove, cost the Yankees about 14 runs each season with his allegedly shoddy play, the SAFE model only considers the fielding of a "grounder ball-in-play" to have been successful when one or more outs are made. So when Jeter goes into the hole with a runner on third and smothers a wicked short hop with a sprawling backhand stab, holding the runner while the batter legs out an infield single, he hasn't saved a run in the SAFE model. Au contraire, my friends, he's failed.
So I've got a few statistics of my own to shed a little fun and perspective on all this weighty science:
- The ten best fielding shortstops according to Dr. Jensen fielded an average of 999.9 balls in play (bip) each season they were evaluated.
The ten allegedly worst fielding shortstops fielded an average of 1,120.7 bip per season. Jeter fielded more balls per season than all but 6 of the 66 shortstops evaluated. Hmm.
Using a simplistic stat (rbi + runs scored) to estimate the run production (as opposed to cost) of shortstops in this study, we find that Jensen's Top 10 fielders averaged 71.81 runs per season . . . and that includes A-Rod, who played shortstop for Texas during part of this research, and who alone averaged 245.25 runs per season.
Derek Jeter's run production, on the other hand, averaged 179.75 per season. Yeah, get him off the field and get me one of those good-field-no-hit artistes! Jeter's costing us big time.
Mark Twain said there are three kinds of lies: lies, damned lies, and statistics. Just ask Professor Jensen, who was surprised to find his SAFE model identified Boston's Mike Lowell as the fifth-worst fielding custodian of the hot corner. Said Dr. J., "I'm very surprised he would come out so low on our measure. I watch a lot of Red Sox games and he seems to do relatively well at his position."
By the way, I lied about Mark Twain. He only popularized the phrase about statistics. It was actually coined by Benjamin Disraeli. Honest.