Kaido has haxxed Zoan regeneration and was basically receiving all the damage the Supernova were dishing out (the moment they decided to actually focus on Mama, she was summarily dealt with).
The Roof Five pushed two Yonkou much farther than 5 Pre Udon Boundman would have been able to push just Kaido. The average level of the Roof Five >> Pre Udon Boundman.
Neither current feats nor portrayal place Luffy above Zoro. In fact, Zoro has the two best feats on the Rooftop by a mile. This is all the more insane if you consider that Asura still exists.
The Supernova are already badly injured and exhausted whereas Kaido is virtually fresh:
- Redon said that given how heavily injured the three main damage dealers of the Supernova were, he doesn't think they can beat Kaido in 10 chapters.
- I'm guessing he's referring to the captains.
- The Supernova stressed last chapter that they've been through "Hell".
- Luffy said that he's been to Hell and back a few times already.
- This chapter is literally titled "Hell".
- Kaido is facing a Roof Five that are far from their peak.
- Any feats he performs against them should be interpreted in light of that.