I played against a similar pusher yesterday. I won 6-3, 6-1. I realized I should have won 6-0, 6-0 but it obviously did not happen. The main problem was putting away high floating short balls. I was overhitting them. In the second set, I added more top spin. But once you come in to attack the short ball (and they are waiting for you to do that), you better put it away for good, and if you don't, be prepared to stay your ground and volley. They are waiting for you to overhit, or get too cautious and not swing freely, then they want to pass you or lob you. You have to swing freely with topspin, and be prepared for them to run like crazy and retrieve it, and then you need to put it away with a volley.
In the backcourt, they are waiting for you to swing hard (or overhead smash) at a high ball and miss, get cautious, and start hitting tentatively, getting tighter and tighter, while they jerk you around. Again, from the backcourt, you have to swing freely, and you have to resist the temptation to slice, and you have to try to place the ball, not go to the middle due to fear.