I'm a huge powe fan, and have been disappointed by his dropoff this year. Part of me wonders, though, if this dropoff is in part due to Doc's tendency this year to play full first and second units. Last year Powe played much more frequently with starters, which meant he faced fewer double teams and had better teammates to pass to.
I think that is part of it, but really it has more to do with Powe becoming an everyday rotation player rather than a 9th or 10th man. Last year Powe was in a platoon with Davis, where Doc did a tremendous job of putting them both out there only when they had favorable matchups. He was able to get the most out of both of them while hiding their weaknesses for the most part.
The biggest reason he was able to do this was because they had Posey taking up many of the minutes at the PF spot, so they only needed 3 big men in any given game, with the 4th guy only playing spot minutes.
This year, they have had to make up a big portion of Posey's minutes with Powe and Davis, forcing them both to be out there every game, regardless of the matchup. They both have been very good in some games, and very bad in others. It isn't really because either has regressed (I actually think they both have improved), but because they are being asked to do more than they were last year, and play out of their comfort zone.
I expect both of them to be significantly better by the playoffs (and I think they have been improving throughout the season), and I also expect them to pick up another big man so Doc can go back to maximizing both of their talents by using them as part time players.
The real problem with this bench is in the backcourt and on the wing, where no one seems able to set up the offense, or consistently stay in front of their man.