If you're a successful club, players won't want to leave. ATM, we're pretty crap, and all the players who have been at the club for 8 years, if 1 of them bolted for free agency, it probably wouldn't make much of a difference. So either you're a great team and players want to hang around and/or sign with you, or you're a crap club that is rebuilding and it won't make a difference.
It is important that players can't leave whenever they wanted. If that was the case, we may as well be renamed to the LA Clippers.