I think it captures a combination of stinkiness and playing time. A guy like Nieves may stink more, in the platonic ideal sense of a bad player, but even Riggles was smart enough to limit his playing time so the archetype of stinkitude was not soil the dirt around home plate more than 158 PAs and less than 400 innings in the field.
And 158 PAs and 400 innings was STILL too many! There were times when a blank space in the batting order would have been better!
