The Highest value when you sell a new player on the first day is 80%.
This means you havent't sold any player in the last 14 weeks.
If you have sold more players in this time, the start value would be smaller and smaller.
When the penalty system was introduced, I received 27%^^. Because I sold lots of players before.
I think 5 transfers in the last 14 weeks don't change the value.
When the player is 14 weeks in your roster you will always receive 97%.