PPG, FG% and FT% is down from last year, while his turnover numbers have increased bigtime.
On the other hand, Powe's assists and blocks have both doubled this year, his free throw attempts are up, and while his scoring is down, his shot attempts are also down.
At the start of the season, they did a lot of isolating him in the post against bigger opponents, often without anyone on his side of the floor to pass to. More recently, they've moved Ray or Pruitt to a better position to receive a pass, and Powe's been doing a better job of finding them (hence some of the assist numbers). And I actually think his defensive rotations are much better this year...I think the block numbers show he is getting himself in better position. Not perfect, but better.
Powe is what he is, he does have his limitations. When the team is going well, he can be a very important piece, scoring easy baskets, getting the other team's bigs in foul trouble, playing physical defense, etc.; but he's not a guy who is going to get the team going well on his own and carry it on his back. Where Powe is at his best is finding open space around the basket ready to receive a pass, banging on the boards, blitzing the roll and defending in the post. The way the team has been using him, isolated on the post or trying to guard more perimeter-oriented PFs, much of those strengths have been negated. He's not a guy who is really going to create shots for himself -- you see him at his best playing with the starting unit (see his game when he started a C against Golden State for example) or when the second unit is doing a good job moving the ball and/or driving to the basket (TA being out has probably hurt Powe's offense a bit, although Pruitt has given him a couple of good feeds in the past several games).
I write all this, BTW, as a guy who bought a Powe jersey last year and wear it to the games I attend, so I do have my biases.