I've made a bunch of other suggestions, but in my opinion this (including capping distance on teleportation), and the second pass on the physics are the most important items for the growth of the game. Most of my other suggestions are icing on top of the cake, but these are far more important for playability. For example, if I'm moving around using teleportation then I can choose to stay in the back court and then my opponent will never be able to put away a ball because I always get teleported right to the spot. Consequently, I don't have to hit good drop shots because if I miss high there are no bad consequences.