I got this extremely easily, what I did was started a new dynasty. It doesn't matter if you create a coach or use an existing coach. I chose to use an existing coach, by picking the head coach of Alabama since they are already ranked number one. Then I kept the default settings except for custom conferences. I moved Oregon and USC into the sec west conference along with south Carolina and Georgia giving me more ranked team in my division. Then I started up dynasty.
Next I clicked the set up recruiting board and created prospects. I created prospects for Qb,Hb, Fb, Wr, K, P, Mlb, TE, SS, FS and Cb. I maxed out their stats in the categories that are important for their position all these players were made as seniors in high school and from Alabama. Alabama is your main pipeline state for recruiting. I then hit the skip to recruiting and clicked search and searched for prospects in Alabama. I added every player that was a 5 star recruit (all the prospects I just created and more) as well as a few 4 star recruits. I then searched recruits that Alabama was their top interest and filled the rest of my recruiting board.
I then went to custom schedules making sure I faced ranked teams for the majority. I turned off autosave and saved my game manually. I then went to team management, edit roster and made most if my starters maxed skill at their important abilities. Hit start season and save. I then simmed my whole season winning every game. I saved before bowl season and continued dimming, making sure i continued winning. I won the bcs championship and simmed the offseason. The achievement popped after the offseason ended.
This only took me 15-20 minutes and i unlocked both this achievement and the one for having the number 1 ranked recruiting in dynasty.
It worked first time for me, if you vote negatively please leave a comment as to why. Thanks!