Maybe teams that list a player shouldn't be able to use them in their lineup after they have a bid or are listed at all. Teams that are selling a player don't play that player after they have a guaranteed commitment to sell or trade.
That is an idea. I see just one con here in a very specific case. After the draft, it happens that I list a draftee and give him 48 minutes at a specific position to the benefit of the buyer, be it arranged with that guy or in the purpose of appealing to potential buyers.
It could be a Problem if the Player is set in a lineup and then gets a bid, is removed from the lineup, which in turn results in a walkover.
Once listed a Player cannot Play would be a simple and clean solution, that would result in even less Players on the market though.
Größter Knecht aller Zeiten aka His Excellency aka President for Life aka Field Marshal Al Hadji aka Lord of All the Beasts of the Earth and Fishes of the Seas aka aka Conqueror of the Buzzerbeater Empire in Europe in General and Austria in Particular