I don't think it was that Chris isn't sharp, I think he was showing proper deference to a man who, despite the fact that he is total scum, was President of the United States for eight years (eight long, long years!).
Chris is ordinarily very sharp and IMO a very good reporter.
But that shock and deference is exactly what Clinton intended by his aggressiveness, to put the questioner off balance and let Clinton unload a pack of unchallenged lies. It's the "feigned indignation" that Dick Morris talked about.
Mary Matalin said the same thing the other night, that Clinton does this kind of thing on purpose (but I do think he got carried away more than he intended).
I give credit to Wallace for his self-restraint, when Clinton started tapping his bony finger on Wallace's notes I don't know how he managed to keep from breaking it off and giving Clinton a new suppository.