Maybe some of the active or former pros on here can answer this question, how can a boxer fight up and down to the level of their competition, for example you could perform well against a good boxer but have a bad performance against a low end journeymen. How does one get caught up in fighting to the level of their opponent?
Preperation. And then the mental aspect. It's really easy to get stuck in a mental loop. Whatever that loop may be.
Well sometimes it mental, sometimes it is attitude and complacency. But I also think sometimes you have to look at the opposition, when a fighter gets in the ring with another good fighter, that other fighter comes to win, they throw punches, they want it, so there is opportunity to land your own. Of the reverse, get a journeyman in the ring and sure they come thinking they may do something but the reality is they are there for a payday and to survive, give somebody rounds, an experienced journeyman can be a much harder nut to crack and open up because they won't engage, won't take any risks. So a good fighter can end up looking awful against a journeyman.
It's a mental thing and method of approach. I used to do it with opponents which I had no fear of and beat them in a 2nd gear, chess-like fight instead of just steamrolling them. This often worked and required very little effort, but sometimes backfired if I tapped into their strengths instead of exploiting their weaknesses. Giving them confidence and not folding even when changing toward a more agressive style. I see boxers do the same, and even forgo training for lower level opponents.
I think its a little bit of fear that ramps a fighter up. The fear that "if I don't watch out, if I'm not at my best, this guy is going to mess me up". I think that's what makes a fighter sharper, more determined and focused. When facing a guy that they know they can beat people often slack off and cruise.