He didn't get shafted at all. They are just dealing with a much stronger Kaido with more at stake so everything's been taken up to a higher level. What was impressive isn't as impressive as it was in the past.
I've actually cover most what you talk about in some of my other post so I'm going to post that here.
Let's talk about the difference between being Law Zoro's asura mode attack.
When Kaido was hit by Law's attack it didn't even slow him down. He continued fighting and called Law's power troublesome.
It's kind of interesting because when Kaido was talking about Zoro's sword, enma, certain fans gave Zoro's achievements to the sword yet, when Kaido talks about Law's DF power they they are quiet.
When Zoro cut Kaido he may not say as much as you wanted him tay but the scene and Kaido's body language says it all.
We can tell from Kaido's face when Zoro cut the attack caused him a tremendous amount of pain.
When Kaido's examining his injury he's shaking and trembling. He didn't have the furious look on his face when he calls out the Zoro and he still. Kaido is still shaking and trembling when he tells us Zoro's attack believer scar.
After he performs his thunder attack we see Kaido is now huffing because his injury he sustained from Zoro.