I agree with that, fast trainers don't have to be good performers. My fast trainers in my High Q team don't perform well, they're in a team where they're qualitywise not the strongest. Point is, without buying green packs they never really catch up, so I kinda feel it's a bit of a waste there, (expensive) but I'll give them another season. My fast trainers in my low Q team are the strongest (quality) in their squad and they perform outstanding. It's just sth I noticed with my teams.

Also, like khris pointed out in another thread, wage/marketvalue ratio is the perfect way to spot a fast trainer. And it can be easily proven. A fast trainer gains quality and marketvalue rapidly while their wage stays the same for at least 1, and max 3 seasons. So, high marketvalue and low wage is what you want.