Play through the entire season and save at the Pro Bowl. Simulate the Pro Bowl and go to off-season schedule/player progression. Look for young players from other teams in positions that you need that have progressed well. About +7 overall should be sufficient. After that, look at your players to see those that have progressed negatively. Quit the game and reload your previous save game. Trade away all of your players that have progressed negatively for young players that progressed well.