Inside the Numbers – Seager’s Defensive Index Rating
Mariners third baseman Kyle Seager was announced as the Rawlings® Gold Glove winner amongst American League third baseman on Tuesday. While we don’t have final vote counts, we did find out some interesting statistical information today when the SABR Defensive Index final ratings were released for the 2014 season.
Kyle had the 3rd-best SDI in the American League at 17.9, trailing only Oakland’s Josh Donaldson (21.2) and Kansas City’s Alex Gordon (19.9). It is interesting that Seager trailed Donaldson, also a third baseman, which means Kyle likely overwhelmingly won the vote amongst American League coaches and managers. Seager also all Major League third basemen with a .981 fielding percentage.
For the second consecutive season, the SDI was used to help select the winners of the Rawlings® Gold Glove Award. The SABR Defensive Index accounts for 30 total “votes” — or approximately 25 percent of the Rawlings Gold Glove Award selection process — which are added to the votes from the managers and coaches in each respective league.
Here is a description of the SDI:
The SABR Defensive Index draws on and aggregates two types of existing defensive metrics: those derived from batted ball location-based data and those collected from play-by-play accounts. The three metrics representing batted ball data include Defensive Runs Saved from Baseball Info Solutions, Ultimate Zone Rating developed by noted sabermetrician Mitchel Lichtman, and Runs Effectively Defended based on STATS Zone Rating and built by SABR Defensive Committee member Chris Dial. The two metrics included in the SDI originating from play-by-play data are Defensive Regression Analysis, created by committee member Michael Humphreys, and Total Zone Rating.