And what about on the other way?
Is not necessary to have from this feature any extra money (shirt sales, whatever)... however is normal that if there is any player which plays excelent for a very long time - his younger or weaker fellows will start to honour him more and will give to him slightly more chances on the field to show himself...
...there could be every time only 1-2 (just a little amount) of stars of the team, however if there are - they should be liked by your players... even with a negative effect if you sell him (falling GS or something)