well, only a couple of players are worthy to invest
those with green color.
Keep the orange to stay low in quality
and the blue ones (but do not invest to them)
Buy some low 3* players, to complete a 14th squad.
Sell the rest.
why to keep blue ones??
seeing his squad he keeps a 100% team.
they won't be 100% next season (provided he doesn't invest mad amount of rests) and they will cause quality increase....!!