I never understood that angle nor the purpose of it.
Jack would often brag of having been a boxer in the Navy but would always be a total wimp.
He lacked any self defense skills. He had to ask Teri to teach him basic self defense that she learned from her women's group.
Because he only had to win one fight to be champ.
And why wouldn't it be possible?
That's why he's afraid to fight, because it would be too embarrassing if he loses, so he would rather turn it into a mental competition.
A person that couldn't be an elite navy boxer would lack the nuance because boxing is nerve based, not strength based, so the sensitivity he has at a cook implies he would have the ability to change and gauge his power and that change is what is needed for a knock out, not brute strength.
That's what boxing is but not what we want it to be so arguably it's that a little less in modern times but fundamentally that's what boxing is and the cooking sensitivity is a big tell.
Plus he only had to win one fight to have the title out of ten, too. At a minimum, that would be the requirement, something like that. Or he could have been undefeated, who knows?