I think they either need a Center with a post game (Jefferson?) or a dynamic PF (Smith.)
The problem right now is the roster depth is great, but the fit is terrible. Reminds me of a talented version of the 07 team. They need to consolidate some of the depth and establish fit.
The SG situation is going to be hard to manage when AB gets back: Lee, Terry, AB, Barbosa fighting for 58 minutes. Any two of them can reasonably take all of those minutes, which wouldn't be a problem if they were an option at SF (they aren't range from too small, to way too small), but with Green and PP, none of them should see SF minutes.
KG is a C. If you didn't get that memo last year, sorry. But it's where he's going to play outside of a starting caliber center with a good post game coming to the team. Even then he'd still play a lot of C.
PF situation is a mess too: Bass, Wilcox, Sullinger all need minutes to get going. But with two small forwards playing at times, that crunch is harder. Playing these guys at C isn't a great option either.
In terms of trades, things get difficult. I'm assuming Danny is not trading KG, Pierce, or Rondo. There's certainly no promise of that, but it just seems unlikely. Everyone else is move-able. Seems like AB is the best young guy teams might like, but probably they want to see he's recovered. Sullinger could play himself into trade bait. Someone might just like Melo. In terms of salaries, it would be weird to see Lee, Terry, Bass, or Green get moved. But if they pull a trade off, one, maybe two of them have to be involved.