Let's not make Herbie any angrier. The post from @sgt5 below explains it really well.
Basically if there is a player you're definitely going to trade out (Danger) but he's playing early in the round (eg tonight), you can avoid the heartache of not knowing whether the guy you want has been selected by effectively "parking the trade" in another player (who plays later in the round) before choosing your desired player. You can only do this if you haven't also used your second trade.
I'm not game to try but I can't argue with the logic.
Basically if there is a player you're definitely going to trade out (Danger) but he's playing early in the round (eg tonight), you can avoid the heartache of not knowing whether the guy you want has been selected by effectively "parking the trade" in another player (who plays later in the round) before choosing your desired player. You can only do this if you haven't also used your second trade.
I'm not game to try but I can't argue with the logic.
Soccer training for my son