I think this would have been a good addition to the game, especially for the serve return.
That's why it's very hard to balance it and integrate it in a realistic way into the game.
One way of doing this would have been making this shot as bad as the acceleration when not well prepared, while making it only usable to force the error rather than hitting a winner when well prepared. If the opponent does not read this, then they are forced an error but if they read it well or have good speed/positioning stats, then they are able to counter it. Moreover, if a player overuses the deep shot, the opponent will position accordingly and the potential to force an error will be lost.
basically, just follow this rules will result in balanced game:
Good positioning:
Regular shot has low winner potential, low chances of forcing the error
Deep shot has low winner potential, high chances of forcing the error
Acceleration shot has high winner potential, medium chances of forcing the error,
Bad positioning:
Regular shot has low chances of self error
Deep shot has high chances of self error
Acceleration shot has high chances of self error
Another thing it would do is make the opponent guessing between positioning for acceleration or deep shot.