I understand completely. The dukes were also damaged by kaido prior. Also lost limbs prior. Were also weakened prior since going in and out of so.long affects them. So their is no excuse in this case period. Hence why I said every fight good or bad is circumstantial
Inu/Neko have been portrayed as basically equal to Jack since Zou. They both fought him equally for 5 days.
Jack>Inu without Sulong as evidenced by this chapter, due to the injuries Inu has. That IS being taken into account.
The point is Sulong is broken and can defeat a weakened Jack 1 hit.
It's ALL circumstantial for sure, but there is an actual explanation for why Inu and Neko won these fights.