I spent ages trying to work out the best way to do this. My top tips are:
- Choose a fast-running team. The Ninja Blacksox worked well for me as their first three runners are amongst the fastest.
- Bunt.
This second point is something that I discovered about 20 minutes before I unlocked the achievement. It works so much better than playing against some of the most brutal AI ever programmed.
How to bunt to success
Basically, if you press the Y button you complete a bunt, which is essentially hitting the ball into the ground. There are three bunt stages, which are achieved by pressing Y once, twice or three times. I had most success with the second stage. (This makes more sense if you give it a go in the game).
As the ball was pitched, I hit it about 80% of the time and held the L stick left to nudge it into a limbo area where there are no fielders. I then had the entire team running one base at a time with each successful hit. Got to 5 in my first try before my three players were out, then got to 9 in my second try and the achievement popped.
Bunt! Bunt! Bunt!
(I hate this game and have now deleted it)