I think many would be surprised at how many "great trainers" don't do any day to day gym work, don't devise or teach the fight plans, but show up a week or ten days pre fight to learn the plan and terminology, then do the fight on television.

In many cases the attraction to a particular gym isn't the trainer, though it is sold that way to maintain reputations and cash flow. Guys follow good sparring and learn from that, not the "great" trainer. One of the current greats isn't the top attraction in his gym; he's third, behind his father and the sparring.

Once you get a guy, a champion, you become the guy, and, generally stay the guy. One of the top guys now has never started a guy that amounted to anything- years ago he stole a fighter somebody else built and that made a name. Money guys believe in him so he gets top guys and they often do well, though he had one go bad and a lot of people are smirking at that.