Ian Mahinmi has been developing nicely behind Hibbert, and looks like he could step into a starting role, but he obviously won't get a chance to start in Indiana. He's one of the few bigs that can play the pick and roll, and protect the rim in the half court, as well as up and down type of games. His offensive game is better than what people probably suspect. I think he would get better playing starter type of minutes.
Wes would really be able to dig his heels in and play tough D with Hibbert and the rest of the Indiana D behind him. He's a clutch shooter and could stretch the floor for Paul George, which is an area of the game Indiana currently struggles with. Indiana wouldn't require Wes to make plays off the dribble, where as Portland could use that option in an off guard.
Plus this draft seems like it's stocked with back up centers so Indiana wouldn't have a problem replacing Mahinmi.