[Muzamba]

Suggestion:
A player may be more likely to sign with a team that has relatives, friends, or former teammates/coaches on the roster. (To implement the "former teammate/coach" aspect, the game would have to keep track of how many days each player has been on the same team with another player/coach and may even take into consideration his morale while on the aforementioned team.) Conversely, a player may wish to avoid playing on a team with an "enemy".

Reason:
IRL, players typically choose to play on teams with players they are familiar with. (see Roger Clemens & Andy Pettitte)

Priority:
I can't imagine how complicated the "Familiarity Index" would have to be for this feature to be effective, although I'd love to see the game at least take relatives, friends, and maybe enemies into account. So for a complete "Familiarity Index", priority is VERY LOW. For a basic one, I'll go with MEDIUM-LOW.