Remain idle while pitching and the announcers will start taunting your pitcher.
If you have a franchise on this game, go to the main menu of franchise mode. Once there, go down to "GM Office", then go to "Roster Management". Select "Player Editor" and use the Left Analog-stick to move left or right to find your franchise team. After finding your team, the game will show a list of all the players on it. Go down to any one of them and you will be able edit their attributes to make them the best as possible. Do this to every one of your team members to dominate the league.