I wouldn't blame him much, if at all. He handled things the same way he always had, didn't do anything out of the norm., handled the information and followed protocol. I guess I'd blame whoever created the protocol for the information not going from Tenet -> Bush -> action quick enough.
The interviewer was pretty much... doing a better job spreading his propaganda than he was interviewing. A bunch of one sided questions, and backing into corners. There were a few points where I was surprised Tenet didn't just walk away. Blaming the death of 2-3k people on one person, and saying it to that person's face? Not that journalistic.
Also: Iraq. Amazing how much was taken out of context from Tenet. He shows, a few times, his views regarding Iraq are far from support. He makes it pretty clear that the "slam dunk" thing was taken hella' out of context. He questions our involvement in Iraq as much as the next person. The interviewer just couldn't accept that.
Afghanistan: I'd say they did okay. Nobody should blame the CIA for Bin Laden's escape. I'd probably blame the military for their lack of involvement. More funding, planning, and support, and we would have caught Bin Laden. Although, with the damage that was done in Afghanistan, I'd consider Osama's capture rather minute. Not much he could do after all his guys were taken captive or killed.