When you start the season, choose one minute quarters, then simulate the preseason, regular season, and the playoffs. This should take you to the option to play in the Pro Bowl. Choose to play the Pro Bowl and play the game all the way through, win or lose. Run the clock down as much as you can to get done faster (don't run out of bounds, complete passes, avoid penalties; etc.) The achievement will unlock AFTER you get back to the main Franchise screen, displaying the two Super Bowl teams, so don't worry that it didn't unlock for you until then.
Enjoy your 10 Gamerscore!