Look mate, I think you missed the core of this game, which is economy. You really need to build up your arena, and since you're playing for a long time now, you should've finished it already.
Basically, you need to improve financial strength of your team, so you can support more expensive rosters. Arena is the way to go there.
Second, you need to train better. I suggest you try to make salary efficient players, not studs(if you mean high potential, high salary). You should try to get players with good starting skills, regardless of potential. Then build them up so they have a lot of skills on small salary.
I'm doing the same currently. I'm currently training an allstar, but I believe I can pack 110 skills into about 35k salary. And I'm using a cheap level 3 coach, and my trainee had normal starting skills, nothing special, I just got him randomly im my first season.
For example, my second trainee was a 19y MVP, but I didn't bother to train him up to 200k salary, I will just train thim with my main trainee at about 35k salary, maybe I continue training him, after my main trainee is capped, up to 50k or so. He will also be very salary efficient.
And I have a third trainee, also allstar, a bit weaker then the main guy, but he'll also have 100+ skills at 35k salary.
I believe my trainees will become very good and cheap backups for top leagues, and probably get a lot of value at the transfer market. Especially when they finally remove the blank lineups, and people start looking for low salary-high quality backups.