I know there is already a sub-forum for players to seek and join associations. However, those players not always have the evidence to prove their value for associations to be willing to accept them there. On the other hand, associations can not always verify this information and have to trust what players tell them. If I'm wrong please delete this suggestion. Thanks.
My suggestion is that an statistics sheet with players performance information of every associations they've been part of is implemented to the game. Something like:

Jan Feb Feb Mar Apr May ...
Managers United. The Fellowship
4 weeks. 10 weeks
16 matches. 20 matches
10 victories. 20 victories
6 loans. 0 loans
4 bonif. 12 bonif.

Maybe not now. But, in the distant future... after my first suggestion is implemented