I personally can't stand Roach and his BS talk, the poor guy is trying too hard to be charismatic, but it's a skill he lacks. But he's a DAMN good trainer, that's for sure!
I think Khan already had the speed and the workrate, Roach has him thinking more, and given him a much tighter defense.
Roach best specialty are against offensive and speedy fighters. But he teaches nice defense and workrates too. He had problems with guys like great boxers such as Hopkins and Dela Hoya. Because its not their style which makes a conflict of the gameplan.