Range Factor
Introduced by Bill James in his first Baseball Abstract in 1977, Range Factor is the number of successful plays in the field a player makes per game: (putouts plus assists) divided by innings played * 9. (When innings played is not available, games played is used.)
Criticisms of Range Factor[edit]
A major critique of range factor is that it does a better job of measuring fielding opportunities than fielding prowess; players who have more balls hit at them tend to get better range factors than fielers who see fewer balls, given the same level of underlying ability. It also does not seperate out the role of infielders involved in turning double plays, which doesn't involve "range" at all.
Because it was one of the very few fielding metrics around for a long time, it bears the brunt of that fact. Nobody complains that OBP treats a walk the same as a homerun, because it is apparent that that's what it does, and furthermore, we have other ways of looking at walks and HR outside of OBP. Range Factor, which is akin to OBP (plays made per 9 innings played), didn't have anything superior to it, and so, bears the brunt of not being good enough.
Obvious changes to Range Factor could be based on per 27 balls in play (excluding HR), to account for the strikeout tendency of the staff. Other changes could be based on per 16 balls in play by righthanded batters and per 11 balls in play by lefthanded batters, to account for the tendency of the batter to pull the ball. Yet another could be to treat the Assists and Putouts separately. And on and on. In short, the main criticism of Range Factor is that in attempting to do more, it didn't do enough. But, with so many other better ways of evaluating fielding, Range Factor can now keep its place as a supporting metric.
There have been several efforts to improve upon the basic principles of Range Factor, including Tom Tippett's Adjusted Range Factor, Pete Palmer's Fielding Runs and fielding Win Shares. All have been supplanted by metrics that rely on play-by-play or Zone Rating data.
