why skills improvement is grayed for one category ?

[meis]

Don't worry much. As he gets more training and games, eventually you will be able to add stats to his defending skills, it will be ungreyed real soon

[shwanko07]

don't worry much, as he gets more training and games, you will eventually be able to add stats to his defending skills, it will be ungreyed real soon

cheers
but why is that happening? that is what i want to know
is it:
A- player reached maximum potential
B- other skills are unbalanced and there is a ration between them where one shouldn't be that higher than the rest

[Raykco]

Don't worry much. As he gets more training and games, eventually you will be able to add stats to his defending skills, it will be ungreyed real soon

The only way the category will become "ungreyed" is by adding skill points to the other categories. It won't just happen.