In my first season of HBD, the team I took over had 2 very good SP leave for FA with the " you should have signed me when you had the chance" type of message you usually get from a disgruntled player. Now I don't know the circumstances surrounding the reason why they would not re-sign but it may have been that they were willing to the previous season but the lame duck owner wasn't interested in the future of the team he was leaving.
My point is that by allowing agreed upon ownership changes prior to the end of the season provides the new owner the opportunity to set the team for the future rather than just grabbing a new team and hoping for the best.