I think personally, this is a bit broken in my opinion.
For instance, this week i got 2 and a half balls. Last week I sold a trainee. prior to that i sold trainee's. Prior to that, i sold a guy who was a star player, but in June - 6 weeks ago.
Prior to that, it was 3 months before i sold a star player. I have had 1 star player on the market maybe once or twice, but didnt sell, so i think that makes a difference as well.
So in all honesty, since march, ive sold 2 'star' players and twice attempted to sell..... Yet i only get a 2.5 rating in the fan survey - and its been consistently this rating all this season.
Which in my opinion, is bollox.