IMO Start Amir, with Sully.
Let Sully defend and lean on the opposing teams center... say what you want about him, and I'm as guilty as anyone here, he get's to where he wants to in the paint, he's certainly a load near the basket, he's difficult to move, let him grab rebounds, score some, set picks and do some solid passing.
Let Amir defend the PF's, score when he can, and protect the rim.
Zeller and Lee didn't show any type of defensive presence at all. Keep Zeller as a backup center, that's what he is. Keep Lee with the second unit.
And last of all, give Mickey 10-12 minutes a game, develop this kid, he likes to protect the rim, he's active, long and athletic, he stay's home in the paint. He has an impact when he gets in there. He'll make mistakes, yes, but we're not really a serious contender. By the end of the year, he may pay dividends.