Excepting a injury or foul out, the only way to get +48 is dressing only 5 players(or less). As Naker said, even if you give the right orders; SFDC, setting the same player as starter/backup/reserve, let them play-foul trobles, etc...it´s possible that your coach change them if you are winning by a great difference or if it´s a close game.
Best regards.