Till LV16 you can spot easily the faster trainers.
After that, not so easy so you must use the sorting of quality in auctions list (I mentioned in previous posts).
At least you can avoid the slow trainers (example #841)
What you can do with a 2nd class ft depends from your team management.
My strategy is to keep 8-9 ft, train them from (about) 100% q to 120% q at the end of the season and start over again the new season.
Then complete the roster with players from auctions or scout or academy (or nego at old times) without investing extra greens for them.
A 2nd class trainer still can improve from 100% to 120%. Just need few extra greens, for example the 1st class needs 75, the 2nd needs 95-100.
Ok, 20-25 more is not a big deal.
It's getting harder when you want to add an extra position + sa too
or to keep him till his 24 y.o. or to make him +8*
So I will keep ADRIANO above (using the same training system as ROBINHO) , till his 24 and sell R.COSTA at his 21 y.o.