- That's why i think you're overestimating Sasuke or underestimating Kakashi. Sasuke was revived by Karin. That means his chakra was almost at his best. I don't know how you can say he was 75% dead. His only problem was that he was going blind.
- Also, tired(even half dead if you want) or not, Susanoo has the same power. That's what everybody forget. Everybody who talk about this scene are only happy to say that "tired Sasuke beats Kakashi, haha", but they forget to say that Susanoo has the same power, tired or not, they also forget to say that "when Sasuke used his strongest attack at that moment to beat Kakashi, Kakashi used his strongest defense to warp it away", and i saw it more impressiv than "weak Sasuke beats Kakashi". For me this simple action shows that he kamui improved really, and that he could have beaten Sasuke if the fight would have continue.
You can even see that he wasn't feared at all. He thought he could beat Sasuke, and even when Tobi and Zetsu came, he was thinking about to beat the 3 of them all by himself.
But we're not forced to believe the same thing, so you can think either way if you think, but that's not what i believe and you should face that.