For people struggling in the playoffs: it seems that the better you do in the regular season, the more difficult the AI is in the playoffs. The first time I did this my record was 15-1 and the opposing team seemed almost impossible to beat.
Here is what I did: Start a competitive season. I picked San Fransisco for two reasons. One, they have some of the best passing in the game, solid rushing and solid defense. Two, their division only has three other teams (this will come into play later).
To start off, if you are playing against someone not in your division, then lose (forefitting by quitting out will work just fine). If you are playing against a team in your division then you will want to win. Since you have to play against teams in your division twice, this will amount to 6 total wins (against 3 other teams). When you are losing, make sure your total losses do not excess 7 (for the time being).
The key here is to make sure you are the champions in your division (a small cutscene will occur when this happens for all teams in each division). This will guarantee you a spot in the playoffs. If you win against the teams in your division, a 9-7 record should be more than enough (I managed to do it with an 8-8 record)
Now that you are in the playoffs you will find that the opposing team's AI will be much easier to deal with. Now simply win the Super Bowl and the achievement is yours.
NOTE: Now that everyone has cloud storage, be sure to save after each win in case you mess up.