Windler can pass, rebound and defend. He just needs to get confident and consistent with his 3-point shot and figure out how to use his ambidextrousness to finish at the rim. He needs to release the 3-pointer quicker and with more rhythm as opposed to taking his time and using a slow release, like he's aiming the ball. You don't have time to line up the shot and take your time getting it off in this league.
He's in a numbers crunch because the Cavs will surely draft a wing this year, or take a power forward and move Nance to the 3. Windler will be competing next year with Okoro, Prince, and Nance or another high pick at the 3.
If I were the Cavs I would tell him that starting next year he's a 2 and he needs to spend the off-season working on ball-handling and 3-point shooting, especially the catch-and-shoot with rhythm and also off the dribble coming around screens. He's got the height to get the 3 off without it getting blocked.
As a low first round pick he's not making that much money so there's no pressure to move him. He has a couple more years to refine his game. If I were him I'd be watching a lot of Chris Mullin tape.