I agree that there is no great way to judge fielding a 100%, but one metric I do like is fielding win shares.Originally Posted by Cedric
They judge fielding differently for each position since different skills are needed to play each position. For example, when considering how good defensively a catcher is caught stealing is weighed more heavily than passed balls to give a true measure of fielding talent for the player.
It also equalizes opportunities for the fielders like for example, if a team uses left-handed pitchers more often and as a result certain fielders don't get as many chances, that is accounted for.
It's not perfect, but it's pretty good.