This system, documented in John Dewan’s "The Fielding Bible", adds another facet to the shimmering diamond surface that is statistical baseball analysis. It’s interesting as another tool to help us understand how players defend, but seems even more limited than the author of the article describes – the fact that it ignores positioning (not the responsibility of the player but perhaps one of the most important unquantifiable factors in what makes a good team defense) doesn’t even get a mention. On one hand, it conceivably tells us a bit more about the pure abilities of a player (absent their coaches) and how they would do if left to their own devices (how often does this really happen?!). On the other hand, since it lacks one very important position (catcher) and the attendant coaches’ influence on maximizing any given players’ abilities it can’t do much to tell us how a team will actually perform.
Not unsurprisingly Manny comes out quite poorly. As does Sheff. And our favorite defensive whipping boy Derek Jeter finishes last at shortstop, with one of the worst net ratings of any player. So maybe Dewan is onto something.