from my experience, football trial is for us to see if hoes/actresses are converted to become football players, we can see their maximum ability before we made the decision. because after we made a decision theres no turning back.
and mostly the maximum ability are depends on the maximum sex appeal of the girls, even when they are not trained yet on the fitness centre. For example 25/50 sex appeal, compared with 50/50 sex appeal, the result are mostly the same.
So if you have divine girls, even only 1/100 sex appeal, she will be better than mafugly 10/10.
So the point is...
1. The maximum quality of soccer players depends on their maximum sex appeal when they still hoes/actresses
2. Trial are needed just to see from 4 skills availabe, such as def, pas, sho, and dri, how many points she can finally have in each those skills, before you decide to convert her. (Warning : no turning back)
As for I am, If the girl are more than 60 on maximum sex appeal. i always do the trial, because i need to know exactly before i decide.
And if the girl are below 50 (mafugly to more than average) i never do trials, i just do the conversion (and wishing the results are good so i dont have to delete her)