Well, I salute for having an operation without anesthesia, you're tough no bs.
However, imo, I don't think Oda would make Cracker say that if he actually isn't a glass cannon.
I know BM sent Cracker and Brulee to deal with Luffy and co. because she knew Luffy had defeated Doffy but BM can be wrong.
Turned out she was actually wrong as Luffy and co. got passed them.
Also, the main reason why Luffy had a hard time against cracker was because Cracker can make unlimited Biscuits.
Like I said, it was a matchup issue.
I still stand by my opinion that Doffy is stronger than Cracker.
Especially, Doffy is going to be a bad matchup for Cracker as Doffy can 'fly' and I don't think Cracker has an answer for the Bird Cage.