It's simple : allow us to use training points in another way.
Such as paying 10 gold balls for exemple to use 10 points in "blocking" transfer it to another skills.

Exameple : a defender dont need "dribbl" and has 300 in dribbl, we have to pay 10 gold ball and the 300 will be decrease to 290 and then we have 10 trainings points available to put in another skill we want....

There, there is more options to use gold ball won in tournament to train players

Now that's not a bad idea however I doubt they would allow it for only 10 plus don't forget some of those are still useful so you would not want to reduce them too much