I’m cheating a bit this week as I’m not so much offering a Web Pick, but a collection of them on the same topic. Most baseball fans are well aware that the established stats used to evaluate defence, fielding percentage and errors, don’t tell you very much about how good (or bad) someone really is.  You can hazard a guess that a player who amasses lots of errors is probably not too slick with the leather, but that’s about it. 

Offering much more than broad generalizations with fielding stats does seem to be a tricky task.  There are so many variables on any given play that, as a fan rather than a statistical analyst, my preconception is that creating reliable statistics is always going to be a major challenge.  Even something as simple as a second baseman fielding a grounder depends on lots of factors.  For example: how hard was the ball hit, was the ball’s bounce affected by spin or a bad hop, how much was the player’s ability to field the ball affected by his initial positioning (good or bad) and who was responsible for that (e.g. was the play made easier because the second baseman’s manager had instructed him to stand a few yards to the right of where he would normally)? 

It’s a major challenge, but clearly it’s one well worth taking on because getting a better idea of a fielder’s ability is crucial to General Managers and very interesting to most of us fans.  MLB.com helpfully provided an article about the latest defensive stats earlier this month and included a separate page containing “a quick primer on four of the newest defensive statistics”.  They’re a good starting point for anyone interested in the topic. 

The MLB.com article specifically refers to the importance that the Red Sox and Mariners are giving to defence and Geoff Baker of the Seattle Times posted a fascinating blog about the M’s and defensive stats just before 2009 became 2010.  I particularly liked the bit about Jason Bay’s defence in left, noting that “while baseball insiders will pretty much agree that Bay is no Endy Chavez as a left fielder, there is little agreement on how bad he actually is”.  No single statistic, or even a group of statistics, is going to conclusively answer that question, but that can be said of most things.  Let’s face it, if different surgeons can look at MRI scans of Bay’s knees and shoulder and come to different conclusions on his physical condition, working out precisely how the Green Monster affected his defence is going to be just as open to different interpretations.

Those different interpretations, and different stats, are exactly what makes these discussions/arguments so much fun for us fans, although General Managers that have to make decisions about the spending of millions of dollars might welcome a bit more certainty.