Hi Manu,
I had some gameplay tuning suggestions that I thought I might suggest. One thing I've noticed using players that have very high topspin skill is that they run out of stamina extremely quickly. It makes sense that hitting with more spin is tiring, but its almost impossible to play with a spinny clay-court specialist because the rallies last a long time and the player runs out of energy in the first game. This is the entire point of the top-spin-heavy playstyle on clay, so it seems like maybe the tiredness from spin needs to be lowered.
The other thing that I was wondering about was the use of talents in season mode. If you pick a player to play for a season there is no way to add any special talents, even though many of the players you can select should have some. You are able to change the skills of a player at the beginning of season mode, so maybe you should be able to change the talents as well. Maybe you could give a number of talents based on the difficulty the season is started with (in the same way as experience points).
Thanks!