That's fine. Then they play in the bowl game and transfer when the semester is over. NCAA needs to move the portal back.You think if they were forced to stay through spring, most would stay? A few maybe, but most still would transfer. And they wouldn't want to risk an injury prior to that. Coaches wouldn't want them to stay either if they weren't in the plans for next year.
If that were a local Iowa State rule, it would kill recruiting. No way would that ever be an NCAA rule.

