i believe this or something similar has been suggested in the past.
Other variations along those lines are
- players with higher Experience boost the speed (or performance) of other members of the team (this may happen already!)
So in ur case, the 'mentor' is just the player with high experience.
Its a good idea - I think the increase shouldn't be too much, like 10% boost at a maximum. But it would encourage people to have 'experienced' players on their roster.
it would also increase the value of experience into the transfer market.