Can you do something about guessing? If there's a very early movement to one side or a player stops in one place and waits there should be some kind of
power and depth penalty...it's ridiculous...Also, on grass guessing will be so effective rendering the whole game pointless...I think this is a tennis game, not a roulette game...who picks the correct side at an important point...

If some people want to play like that they can go to Las Vegas and visit the casinos to test their
luck 
Guessing is quite effective in real tennis too but it's mostly for passing shots - guessing in a baseline rally doesn't give such a big advantage like here...it just returns the rally to an equilibrium.
The premium should be on moving well (and constantly moving), not on standing in a spot or moving to a spot 2 seconds too early to bash the next ball...If a player has moved to a side much earlier than the opponent has hit the ball, he should get a power/depth penalty...same if the said player is standing in one position and blatantly waiting for the next ball...It's very lame, boring stuff ruining all the fun...
I think that's the most important issue now, if you sort out the guessing to be more realistic and balance out the movement speed not to favour counter (too slow) or defender (too fast), this game could be fantastic...Already heard people complaining that the offline movement is too slow (will favour counter?), but didn't try it for more than 1 point so can't tell...