2007 (with Brady healthy): 1493 yards, 15.2 average, 23 TDs.
2008 (with Cassel starting): 1008 yards, 14.6 average, 11 TDs.
2009 (with Brady returning): 1264 yards, 15.2 average, 13 TDs.
How exactly did he quit?
There have been a few odd rumblings, and he's not happy about not having a new contract, but "quitting"? Compared to what we expected, he's behaved himself quite well. I watched him at practice in training camp. He's playful with the fans, he signs autographs even when it's not his day to sign, and generally hasn't done anything wrong (especially when compared to players like Ocho and T.O. and some others).
I'm not sure I would break the bank for a guy his age. But he IS one of the best WRs in NFL history, and he's still got some tread on the tires.
Now, I grant you, I'm not sure if he wasn't motivated (i.e. playing for a new contract) if he'd be the same guy. Here in New England, he was trying to show the league he still "had it", and he was (is) trying to finally get a Super Bowl ring. If he went to a mid-level team that probably wasn't going to win a SB in the next year or two, I don't know how he'd act. So he's probably not worth the risk for KC. And, I don't even think he's worth the money for the Pats (who might cover his absence with promising rookies). But I don't think "quitter" is accurate.