Mutant Football League

About the same route i ran.
Work your way up through Dynasty Mode. I was able to pick up 3-4 "legend players" based on cost, and make a few trades every year. I started really trying about the 4th season. You'll want to use sticky ball tricks. It'll almost guarantee 2 sacks a games, so just use your preferred player.
After every game, check the MFL player stats to see who is leading the league. If you're leading, keep up the same method. If not, trade for the players who lead the league up until week 7s deadline. I ended up getting the achievement, off a player i picked from a trade week 4.

This can be unlocked using two controllers. What I did was I assigned the second controller to the opposing team, and I picked a passing play with the dummy account's team, and I assigned a blitz play to my main account's team, then I snapped the ball and stood in the pocket until my main team got a sack, and then I rinsed and repeated this method for all four downs, then when my main team got the ball back, I punted it back to the dummy team, and repeated the same method until I was late in the 4th quarter, where I eventually got my main team to score points on the board to end the game. I only did this during the first two games, just to be sure that I had a comfortable lead for the rest of the season, but if another team catches up and is close to beating your sack record at a later point in the season, just repeat this method to give yourself a comfortable lead. The achievement should unlock at the end of the regular season.