Have you never heard of a shooting slump? O'neal just sucked out there. It had less to do with "great defense" and more to do with sucking.
So how do you differentiate "great defense" from a "shooting slump"?!
That's subjective in large part, unless we all can sit down for a group Celticsblog film session.
I think even if we did that, there would still be huge subjective differences.
But either way, I think Perk's defense is irrelevant. No matter how good he plays defensively, if he plays the way he did offensively against the Cavs, then he is going to hurt the team.