From my exerience the chance to get an offer for 59-79-99% players is like 100 times bigger than not with these %. Like it was said only then they get into negotiations lists, just check the lists that you can see - probably all have 99%. Rarely I saw 98 or 97. Your friends or others who can see your team are able to make offers for any players in your squad (except over 99%, from their view)