Taking a step back defensively has to be a concern for the Rockets this year. As smoothly and efficiently as their offense ran with an integrated Chris Paul last season, they were actually a tenth of a point per 100 possessions less efficient than they had been the year before. Their breakthrough last year was, in large part, because of significant improvement at the defensive end. The departures of Luc Mbah a Moute and Trevor Ariza absolutely threatens that.
Some of those minutes will be going to Carmelo Anthony, a pretty poor defender, and a lot will be asked of James Ennis in filling the gap. Michael Carter-Williams may do some revitalizing for his career but being more of a backcourt defender, he’s not going to help much with what the Rockets lost in Mbah a Moute and Ariza. The best case for the Rockets is that the addition of Anthony is somehow able to take their offense to another level, one that can compensate for whatever step back they take on defense.