Damn, that's pretty clever and epic on Oda's part by having Luffy's first clash of Conquerors Haki that splits the sky in half actually benefit the Alliance in a major way. Hats off to him for that one.
After all the beatings Jack has been through, I can't say he's the weakest. He's arguably taken the most damage ( probably 2nd most ) & got up multiple times. Fought a sulong mink army basically solo. Fought ashura to a stand still even with his swords broken & lasted 5 days straight on Zou while Inu & Neko + their group had 12 hours intervals of rest.
For a 3rd commander being put up against people above his weight class he did good. It's just a shame Oda didn't give him a legimate win ( if you don't count him using the gas ).
If King & Queen go down here then that'll make them look worse than Jack imo. Jack is very damn strong but it's like people only care about the end result and not everything leading up to it, which if you're going to evaluate a character isn't something you should do.
It's just unfortunate Oda used Jack as an example of how "tough/durable" the beast pirates are, when in actuality only Kaido, Jack & Ulti proved to be the tough durable ones since it took A LOT to put them down ( excluding Kaido )
The funny part about "zoro is equal or near Luffy " is that Zoro is steps behind
Zoro is top YC level this arc after getting PUs and will beat a YC while Luffy was Too YC level since DR and surpassed YCs after gaining fS and matched Katakuri
Now luffy is solid top tier while zoro will be sold too tier when they face Navy/WG coz Zoro will be low top when he fights and beat Shiryu not solid top tier