He's putting up decent numbers, but the advanced stats still don't like his contribution. He has a lowly 98 offensive rating and a below average 107 defensive rating. In other words, at that rate, if he was on the court for a whole game and the Pistons had 100 possessions (which is average for a game), they would lose 98-107.
I credit the Pistons resurgence to the other guys. I've always been a Tobias Harris fan. He is still young and looks like an All star. Drummond still misses a lot of rotations, but he is improving other areas of his game. Reggie Jackson finally looks like he is back to where he was a couple seasons ago as an offensive initiator.
All of that being said, I still think they are fool's gold. They probably end up slightly above .500 (43 wins?), but I don't think they scare the Celtics, Cavs, Bucks, or Raptors.