Now on the left column select the Casualty event type, then the same player you gave MVP, and pick death for the casualty option on the bottom. Remove one of the two MVPs that the opposing team earned since you conceded (there can't be more than two MVPs in a game), then on the left column select the MVP event type and select a player from your team. Press triangle and you'll see the option to edit the results of the game.
As long as you're an admin or higher you'll see the option to press Triangle for Advanced Management. Select it and press X for match management.
Now go to the competition and tab over to the Schedule page, you should see the conceded game. Start the competition and immediately concede the game during the inducements screen (keep pressing O and it'll give you the option to abandon the game). Add an AI team as well as one of your own teams. First, create a multiplayer league where you're administrator or higher, then create a competition with 2 teams (make sure auto validation is OFF under competition settings).