Perhaps the skills werent that high. But it seemed to me that you just have some jump shooters on your team (looking at their salary). Were they atleast the highest skills?
The drop is not 2 straight levels, like said before. It's more like, something above one level and they are not dropping every week.
I'll use an example of one half decent sg. 133 skill points (not counting in exp,st,ft), everything at skill level 7 would be 70 point. So in order to reach that, he has to drop 63 points. If he drops one skill every 2 weeks, he needs 126 weeks. That's 9 seasons!!!