This shouldn't be a surprise with the Heat's defensive schemes. They have relied an awful lot on their wings ability to be disruptive to make their defense work well. Ray isn't that sort of defender clearly.
Of course his numbers will improve because right now the Heat's overall defense is dragging so badly, Ray goes with the tide defensively like most guards.
Just about to say the same thing. Their sets rely almost solely on athleticsm. They trap extra hard and switch on pretty much everything so it's tough to make them pay for it. As if that wasn't enough, they heavily load that side of the court using Wade or LeBron as a free safety able to wreak havoc and help at will. They can do this because both guys are quick and long enough to recover in time. And it pretty much begs the offense to attack the weak side by making that crosscourt pass, which leaves whichever one is on the other side to leap into the passing lane and grab it. They never reteat to the line and conservatively get back on the guy, they're expecting that pass.
These schemes can make quick guys like Chalmers, James Jones, even quick bigs like Haslem and Bosh look much better than they are, but leaves somebody like Ray always a step behind because he's constantly being asked to switch guys or recover too much ground, and isn't explosive enough to steal a lot of those passes he's in position to get. That's why they couldn't ever play Stackhouse and released him.