I don't trust Prohm to play the guys who make the team better. He has shown this time and time again (Condit right now, Lard last year, Wigginton last year, Lewis right now)
I love Conditt, but I think people on here might overrate him a little bit. There have certainly been games where he's been the best big man, but that doesn't happen every time out. His blocks and dunks are flashy, while Jacobson and Young aren't, so I think that might be part of it. For instance, against Iowa, Conditt got out of position a few different times going to block someone's shot, leading to an easy layup for a rolling Garza, or an easy put back after a missed shot. You don't see that as often with Young.
As for Wigginton, there were quite a few games, including the NCAA tournament game, where he played more than THT did. Lewis right now, maybe he does deserve playing time, but I don't think you can fault Prohm when you can see Lewis's shortcomings on the defensive end.
It's also not just about what happens on the court during games. I know that a lot of fans don't like this, but there are certainly things that happen off court or in practice that Prohm keeps inside the program that may affect playing time. Obviously this happened at least some with Lard. It could be an off court issue, or it could just be a guy who looks pretty bad in practice or doesn't work very hard during practice. Can we really fault Prohm for not playing a guy in those spots?