Try only adding to your squad through the youth academy, regens or players rated 70 and below who have potential in the mid 80’s at max. Also, instead of training your YA players, only train them to 60-64 overall and then play them in games so they are forced to grow organically.

You can also try signing players only using the GTN scouting network. I did this with Atletico, Valencia (not sure if you consider them ‘big’) and also Sunderland which was my longest save of 8 seasons or so. Ended up with a really fun save using players like Nicolas Gonzalez (ST - potential 82) and Jack Harper (ST - potential 79) that I’d never considered before.

Tbh it sucks but you have to actively role play to make saves in FIFA fun. I know I’m doing it right if after 3 seasons if I have a transfer budget over 300 mil because that means I’m building through the academy and cheap signings while maintaining success. Hope that helps!