This is a good observation that I noticed as well.
I think what happens is that when the ball is hit, the AI determines "the SS is going to catch it", which is the correct call. So the AI is only concerned with the SS getting over there and making the play.
But even though it's the SS's play, the 3B and/or LF should at least run out as well. And in a game that looks so true-to-life, it's kind of jarring to see anything that doesn't look like what you'd see in a broadcast on TV. But still, it's completely an aethetic thing.
As for the debate about stances and correct deliveries, I'm kind of a stickler about that stuff as well, but I think it would be impossible to satisfy everyone in this regard. More important than each stance being perfect, to me at least, is to attempt to individualize every player in the game as much possible, and The Show absolutely does this more than any sports game that I can think of.