For this achievement, you must cause a throwing error to first base with 2 outs and the runner is safe at first because of the error.
Difficulty sliders:
User: Gather error freq., and throwing error at 100, throw accuracy at 0
CPU: contact 50 (he's gotta hit it), power 0 (keep it in the infield), running speed 0 (he can't be safe before you blow the throw)
To make this even easier, don't worry about editing your players, just move them around. Go to defensive alignment, it shows the defense rating for each player at the position. Swap your 1B with your LF, C and 3B etc. so you have an infield that's in the 20s and 30s.
Now when you want the ground ball and have the 2 outs, throw a fastball low in the strikezone and weak to get a dribbler to an infielder. Now max out your throwing slider when you throw and hopefully you get it. Unfortunately you only get 8-9 of these chances in a full game, and you now have a crappy defense. You can adjust the sliders in the middle of the game if you want to set up the 2 out crap-fence to achieve your error.