Doc has some real trouble learning new players and the style they play. It was the issue they had with Finley and Nate last season and now this season with Krstic, Green and the other new guys.
It took him time to learn Nate and Finley and Nate finally fit in in the playoffs, maybe the same will happen with these other guys. Green, Troy and Arroyo will be needed in the playoffs especially when and if JO and Shaq can't play so it's essential that Doc learn fast.
However I still think that Nate's ineffectiveness and inconsistency this season before the trade is because Doc was using him wrong. With the Knicks he would dribble passed the defense and finish at the hoop or he'd do a step back shot also came off screens. With the C's he was a 3pt shooter only it seems and that is the wrong way to use him, he's not Ray Allen or Eddie House... not a 3pt specialist... he's a scorer.