A short anecdote. I was coaching against a team at the college level who had a fat boy at SS. The team ended up winning 40 games and was a game away from the college World Series. All 3 games that we played them, I went back and forth on whether I would have recruited the kid because of his body type, but he got to everything and made every play. The kid ended up getting drafted at the end of the season.
Point is, after seeing that kid play, I don't think it's unrealistic to have a SS that is slow straight ahead, but is quick laterally.