The most important big man on the Nuggets roster is Nene. Denver are going to be better next season because he's returning after missing nearly the entire season.
With Nene and K-Mart they've kept two very good defenders. Both are high quality one-on-one defenders, both play good post defense, both protect the rim, and both a good team defenders. Nene gives them a legit 6-11 260lb presence in the paint who can limit post scorers. Their interior D is going to be better without Camby.
Their perimeter defense is suspect. If Anthony Carter and Iverson are starting again next season it'll be difficult for them to improve there. They need to move both players. Carmelo Anthony on the other hand is improving as a defensive player and became their best perimeter defender (not saying much, still below par but better and close to mediocre) late last season. He's a guy who should improve more next season. Their perimeter defenders will take less chances without Camby back there which is a good thing because they're (a) awful at making that decision (b) Camby was more concerned with his box sheet than stopping the play. Their perimeter defense will still be bad but Camby's presence wasn't making much of a difference anyway.
Camby's selfish defensive ways hurt Denver consistently last season. He regularly stepped back and allowed penetration so he could come over late and attempt to block the shot, instead of getting in the way and denying the easy path to the rim in the first place. That gave up extra easy baskets and extra easy follow up buckets. He's also given up on boxing guys out and gives the opposition unnecessary extra possessions, especially considering how dominant a rebounder he can be when he's head is glued on straight. Camby is also a weak one-on-one defender who's a poor post defender. Opposing big men score on him easily and often, especially post players who have a field day with Camby.
Camby has the ability to be a defensive beast in this league but his efforts have been half-hearted (selfish too) and they've created nearly as many problems as they solved limiting his overall value as a defender.
Camby's offensive game has also become problematic. It's not that he can't do it, it's that he doesn't put in the effort to give his team anything on that end of the floor anymore. He just stands 20 feet from the rim. Last season was easily the most stagnant I've ever seen Camby offensively. He used to create problems with his activity and athleticism which meant the defense had to keep someone near him. Nowadays they just back off and leave him alone out there. He's coming off his lowest scoring year in four years (and under his career average) and his lowest FG% in 5 years (again under his career average). Things got even worse in the playoffs as he scored a pitiful 3 points a game where his lack of scoring/movement allowed the Lakers (Gasol) to send shot blockers down into the paint on all penetration limiting Camby's teammates.
Denver is going to be better than they were last season.
Now if they only started moving out Carter and Iverson .....