Defensive Stats 101

Measuring defense has been one of the most difficult areas for statisticians to work on and new or improved statistics are being made available on a regular basis. The following formulas, descriptions and statistics will provide you with the common and not-so-common items currently being used.

"Nice guys finish last." - Leo Durocher
Defensive Stats 101

Formulas / Definitions / Examples

The Baseball Workshop & Project Scoresheet has been methodically placing the location of EVERY hit ball for EVERY game during the last several years. A Defensive Average, or DA, is the rate at which fielders in their respective "zone" turn hit balls into an out. The zone, or area of responsibility, spans the entire field and no section of the playable field is considered beyond the reach of a fielder. The Defensive Average statistics is nice because it is analogous to a fielder's Batting Average Against in that it specifically measures times reached per opportunity.

 
(Putouts + Assists) divided by (Putouts + Assists + Errors)

The fielding average, or fielding percentage, defensive statistic is the most common rating system being used in baseball today. It is meant to measure the success rate of fielding opportunities by each player. The official scorer for each game plays a role in this statistic by determining if the hit ball would have required an ordinary amount of effort to turn the play (thereby charging an error to the fielder if they did not turn the play) or an extraordinary amount of effort to turn the play (which does not result in an error charged to the fielder). The downfall to this statistic is that it almost rewards fielders who choose not to attempt a difficult play, thereby avoiding the error, to those that try to turn every hit ball into a possible out.

Fielding Runs is a common term for any statistical treatment of fielding that converts a fielder's performance to runs. Total Baseball uses the most common approach and most easily understood version. Their approach involves weighting the number of putouts, assists, and double plays made by each fielder, and comparing those totals to positional norms of other fielders to arrive at a figure above or below average. Each extra out made, or hit allowed, is worth X runs which leads to the FR figure. Career figures are considered better indicators than individual seasons as normalization is required for better overall averaging of each fielder's statistical performance.

 
(Putouts + Assists) x 9 divided by Defensive Innings Played

Range Factor simply stated is the number of plays MADE per game at the fielding position. It is better than Fielding Average in several respects: It can be calculated for almost any player this century and it takes into account the fielder's own ability to get to a batted ball - rewarding the more gifted players at each position. Positions can only be successfully compared to the same position on the field when using this statistic and early in the season numbers are often skewed as players chances are not yet normalized.

STATS, Inc. developed their own defensive rating system to also track locations of EVERY hit ball for EVERY game played - similar to the above Defensive Average statistic. The Zone Rating system is different because the area of responsibility, or zone, for each fielder is considered a "playable" area and does not account for balls hit into "Bermuda Triangles", "No Mans Land" or other impossible to field balls. A fielder that turns a double play is credited with 2 outs in the ZR system as their play on the ball actually resulted in both outs versus Defensive Average which only credits the 1 out. STATS, Inc. books area available at every bookstore and their work is updated on a yearly basis for player comparisons.
Defensive Stats 101


During the 1978 season, Butch Hobson of the Boston Red Sox had a fielding average of .899 which was the lowest by a third baseman since 1916.

Did you know that in 1903, Johnny Gochnaur of the Cleveland Blues made ninety-eight (98) errors in one-hundred thirty four (134) games played at the shortstop position?

Trivia Alert: Roy Smalley is the last Major League ballplayer at any position to make more than fifty errors (he had fifty-one in 1950) during a season.