OK, OK, so I went a few days without checking this forum. Sorry 'bout that.
Adonal Foyle is a pretty good backup center. If he's your starter -- or, really, if he's playing more than 15-18 minutes a game -- your team is in serious trouble.
A lot of Warriors fans love Foyle because he puts so much visible effort into his play. But the reason you notice him trying so hard is because he's physically overmatched in almost every single game.
He's made steady, gradual progress since his rookie year -- his footwork is good enough now to get you a few baskets in the low post, and he even hit two baseline jumpers in a game a few days ago. But when push comes to shove, he's still a freaking 6'8-3/4" center
, and there's just no way you win with those in the NBA ... even if he is something of a shot-blocking idiot savant
. The shot-blocking gives him something of a defensive reputation, but the fact is that taller guys like McDyess just shoot over him like he's not there.
All in all, he'd be a not-really solution to the Nuggets' interior defensive problems in much the same way as Lenard would be a not-really solution to the Warriors' shooting woes.