Among regulars, Prince Fielder and Rickie Weeks are close to the worst at their respective positions: Fielder ranks 33rd of 35, apparently costing the Brewers close to six runs with his glove. Albert Pujols is the best in the Majors at first, and Lyle Overbay (to my surprise) is not far behind.
Weeks's presence at the bottom of the second base rankings shouldn't shock you; regardless of how much he's improved, he's got a big hole to dig himself out of. He's also third from the bottom, having cost the Brewers about 11 runs, or just over one win.
Third base is good news for us: Corey Koskie has the best glove in the NL, and David Bell is in the top half. At short, Bill Hall ranks in the bottom half, but only two runs below average. I asked Marc for JJ Hardy's numbers: JJ has a Zone Rating of .848, which would put him close to the top 10.
Marc also analyzed outfielders. Carlos Lee was a bit below average in left. Interestingly, Scott Podsednik ranks in the middle of the pack among leftfielders. I would've expected him to do better, as a converted CF. However, the White Sox seem to be down on his CF defense--maybe they're on to something.
Brady Clark and Geoff Jenkins are both below average: Brady just barely so, Jenkins costing the Crew three runs, ranked 26th of 34. Sadly, Kevin Mench is between Jenkins and the bottom of that list: at almost seven runs below average, Mench is among the 10 worst defensive outfielders who have gotten regular playing time this year.
It's a little sad that the Brewers defensive numbers are so bad this year; with Hardy out of the lineup, only David Bell is above average among current starters. (I don't have numbers for Tony Graffanino or Jeff Cirillo.) I would never advocate the wholesale remodeling of some team just to get some defensive specialists (especially since Ned would quickly become infatuated with a Brad Ausmus or Adam Everett type), but it's questionable whether this team can succeed with a bevy of below-average defenders.
It'll be interesting to see whether Fielder and Weeks can improve their skills; aside from those two, I don't see a lot of room for improvement. Having Hardy back will be a boost, but that leaves the outfield; perhaps a trio of Corey Hart, Tony Gwynn Jr., and Nelson Cruz (oops!) would be a substantial improvement.