Oda just gave him that spotlight just to hype Kaido's crew and the first character with a billion bounty. In Zou Inuarashi and Nekomamushi sulongs would have defeated him at that moment if not for the poison gas
Inu and Neko + their respective minks also couldn't put Jack down for 5 days even though they both had 12 hours to rest each time they fought, Jack didn't.
It's just funny how a lot of people are willing to overlook what Jack has actually done & accomplished just to shit on his character.
Truth of the matter is, Jack has a better showing than King & Queen, his endurance is better than King & Queen, his loyalty to Kaido is better than King & Queen.
If you look at his record it's also better than King & Queen.
Minks + Inu & Neko on Zou = Win
Fujitora, Sengoku & Tsuru = Lose
Zuneshia = Lose
Ashura = Draw
Sulong Mink Army = Win
Sulong Inu & Neko = Lose
Round 2 vs Minks ( on his way to the scabbards ) = Win
Round 2 vs Inu = Lose
It's funny how Jack only losses were against an enormous elephant & because he fought an army of Minks right before he fought the Dukes.
Ultimately Jack, Smoothie, even King & Queen got screwed by Odas writing.