In my opinion fighters make the trainers 90% of the time. Khan will get knocked out who ever is in his corner
The trainer makes a boxer, that's why it takes years to master the craft. Put two 20 year old Martinez in a gym; 1 with a trainer and 1 without and you will see the difference trainers make
It's a two-way street. Trainers can't fight for their fighters and fighters rely on their trainers insight throughout camp to create a strong gameplan. Ultimately the responsibility rests on the fighter, but the path up to that point is full of guidance from said trainer.