According to what Bouldy said it's because of personality. But I can't see the issue:
Also their determination is the same basically. Santi 15, Paredes 14. I set him to improve his game, and by the looks of it he's learnt the PPM (Which is good as he suits all of them). But now santi's morale has dropped and he's injured
But yeah, I spent ages reading up on tutoring and whats best for each player etc. Santi was a perfect choice for Paredes but then this happens?