"Good strategy on Libby's part, to make the trial into a leak case."
Exactly, the charge is Libby didn't get his story straight about conversations with journalists some months prior. Sort of a memory test with the booby prize a felony conviction--way unfair!
No it's not. The charge is that Libby mislead investigators and the grand jury on the point of whether or not Libby knew that Plame worked at CIA. The charge is that Libby DID know, but lead investigators to think he didn't know (for sure) that Plame worked at the CIA.