Matt Cerrone from MetsBlog.com says he doesn’t think the Mets should sign Dan Uggla because of Uggla’s free-swinging ways. 
While Matt’s right that Uggla is an unrepentant whiffer, he does manage to get on base adequately enough to be a valuable hitter. Uggla posted a .360 on-base percentage in 2008 and a .354 mark in 2009, so he is by no means Jeff Francoeur.
The problem is, he’s a bad defender by just about every standard. The Mets already have one of those at second base in Luis Castillo, so one could argue that Uggla’s offensive upgrade over Castillo — assuming it’s a wash defensively — makes him a nice fit for the Mets.
But with the team’s defense being as bad as it was, it’d be good to upgrade defensively if they were able to somehow move Castillo, especially if they hope to see some improvement out of ground-ball guy Mike Pelfrey.
The Mets seem more likely to acquire Uggla and move him to left field, but that would essentially sap him of his value by moving him away from a premium position. Because Uggla’s actually probably about 5’9″, tops (he’s listed at 5’11”), I’d be surprised if any team put him at first base.
Regardless, moving Uggla to any corner that’s not third base (which, in the Mets’ case, is occupied) makes him little more than a league-average hitter for the spot. Plus there are no guarantees he could field it adequately.
Granted, the 2009 Mets could have benefited from a few more league-average hitters, but not at the cost of the prospects it’ll take to acquire Uggla.
Tedquarters 
Cerroneous is right that Uggla’s platoon splits aren’t pretty. However, it’s worth noting that even against LHP (i.e., his bad split), his career OPS of .761 is better than Francoeur’s overall career OPS of .743. It’s silly of him to lump them together as both being “big-strike-out, free-swinger[s]” without taking note of the fact that Uggla is just a much better hitter than Francoeur, even disregarding the fact that Uggla is a middle infielder and Francoeur is a corner outfielder.
In an ideal world, I’d agree that it’d be great to find a way to deal Castillo (as much as I’m happy with him for the way he played this year, he’s as close to a “sell high” candidate as the Mets have) and replace him with someone who’s an upgrade offensively and defensively. Uggla’s defense isn’t really THAT bad, though, is it? His UZR/150 for his career is only -2.5, which isn’t great, but it’s also hardly Adam Dunn territory. In fact, as unimpressive as it is, it’s a significant UPGRADE over what Castillo has done the last two seasons (-9.3 in 2008, -10.2 in 2009).
So if, hypothetically, you’re determined to upgrade over Castillo… I mean, who else is out there as a realistic option? The only names I’ve seen mentioned have been all-glove guys who would be big downgrades with the bat.
I’m up in the air over whether Uggla’s defense is as bad as Castillo’s. The stats you point out are accurate, naturally, but according to Bill James’ plus/minus he was actually a couple of plays worse than Castillo this year. Plus UZR didn’t like Uggla much this year, either. With defensive stats it’s always tough to make precise judgments, but it’s safe to say they’re both pretty bad.
This is completely out of the blue, and not a Metsish move at all, but I’ve been singing Mike Fontenot’s praises since he was buried behind a few other middle-infield prospects in the Cubs’ system. He had a horrible year with the bat, but he torched the ball last year and has a pretty adequate sample of decent Triple-A numbers.
I’m not saying they should hand a job to the guy, but if they’re looking for a good buy-low acquisition to back up Castillo (or oust him, if he falters) and provide a better glove when ground-ball guys are pitching, he’d be someone I’d consider. He’s supposedly on the block, though I never put too much stock into those types of rumors.
Plus he’d appease fans with his hilarious little-man grit.
Fontenot certainly wouldn’t be a bad option as a depth pickup.