I think that players can drop his skills at different speeds.
But it is random.
Maybe your Role Player
will drop 4 skills at 35 but,
your ATG will drop 7.
Maybe youe your Allstar will drop only 2.
I have had many 33 year olds on my team and I got one drop out of all of them combined(lucky).
I had a 37 year old for 5 weeks, he got 3 drops.
So as you get older you drop more and more.