As I've said before, he knows how to fight, he's trained how to fight. Pretty damn well, I might add. But, he's not in the top ten fighters in comic books.
And, if you count minor characters, I don't even think he'd be in the Top 20.
I also find it funny that, for decades, he's been written as a berserker with government and samurai training. Then, some idiot in the 90's retroactively gave him more fighting skills. All of a sudden he's using techniques that he's never used before in comics past? Combat techniques, at least for a master-level fighter, are instinctually, physically programmed. Although it's fictional, Jason Bourne was a perfect example of this. If you've trained hard enough, then memory will not affect your ability to defend yourself. [As an aside, amnesia doesn't even affect people like this, anyway].
He'd need an impetus to push himself to be the best, to actually be among the best. And, the way I see it, he isn't. Because his powers and mind-set preclude this.