Hunter is a decent trainer.
As the saying goes; styles make fights, maybe this exists with trainers?

I think every(great) trainer has worked with fighters they just couldn't improve_under any circumstances.
A few examples:

Enzo Calzaghe great with Joe Calzaghe-sucked with Enzo Macrinelli.
Freddie Roach got Toney who was already a great fighter-fortunate to have gotten Pac (and Hunter wouldn't look great as Pacquiao's trainer?)

Roach had a fighter named Justin Juuko- Roach did no better with him than Steward with Jermaine Taylor , or in this case Hunter with Khan.