I was wondering if this was a bug or something that has to do with character attributes.
This is most noticeable when returning a high powered serve at any timing (perfect, good, too slow/fast, autoswing). Once the ball is back near the server, my player will attempt to splitstep wherever he is on court, even if it's way outside of the sideline. This keeps me from running back towards the center to try and cover the entire open court.