Y'know I've seen this happening a lot actually.
There's been so many times when a "strong" character gets beaten up to prop up a newly introduced character. But everybody I ask seems to know that the writer is just playing silly buggers to prop the new character up and none of them really buy it. They accept it because the story collapses otherwise, but they recognize in the back of their minds that the writer can do anything, they can make a bear lose to a mouse and just say: "Oh the mouse was really strong", but it doesn't change what the writer is so obviously doing.
Combine this with the character shit-talking it just seems kind of weird. We all know the shit talk is undeserved but have to act like it isn't. Like when someone feels themselves too much and starts talking about how great they are and you know they're just stealing someone else's work but they're signing your paycheck so you can't point out the truth without losing your job.
But in this case, the character doesn't know they're stealing so you can't really blame them and you don't really hate the character because it's just the writer shuffling around unconvincingly when, before, they had managed sell new characters convincingly.
I suspect that having some guy show up outta nowhere and just be soooo strong may be the least convincing way to introduce a badass character, but if anyone knows an even less convincing way, you gotta tell me. Maybe I've just been seeing THIS particular way too much lately.