Naturally, the further away a pitching machine is from the batter, the more curve there will be on a pitch. There is only so much curve that can happen in a very short space.
A 40 foot cage really means the batter is only 30-32 feet from the machine, since neither the machine nor the batter can be flush with the net. That is about half the major league regulation distance of 60.5 feet meaning the ball will only curve about half as much as it would from regulation distance.
A three wheel machine is going to be the best machine for throwing sharp curves, but it would be unrealistic to expect it to curve as much from 30 feet as it would from 60 feet. One of the settings on this pitching machine is the amount of curve and you would certainly want that set to its maximum setting when trying to throw curves from such a short distance.