Rebounding also adds a lot to the salary of the players. It is often wise to train this skill at the end of the training career.
In my case, my three SF trainees are at 9, 8 and 7 rebounding while having a TSP of 122, 115 and 117. I plan to raise their rebounding by 2 or 3 skill points this season. I expect a raise in salary from 33k, 27k and 34k to 40-45k which is quite a lot for 2-3 more skills if you ask me.