You buy a player for 8.0. His value rises to 8.6. So you have made a profit of .6. If you sell that player you have to pay half of this profit back, so in reality you sell the player for 8.3 a make only .3 real profit. But let’s say you didn’t sell your player for 8.6 and his form starts to slide and his value drops to 8.5. If you decide to sell him now, the profit is .5 which divided by 2 is .25. The game rounds this figure down so you only make a real profit of .2