Originally Posted by BevelDevil
It's mainly about the shoulders.
If you try to restrict your shoulder turn on the 1hbh you're likely to lose power and control, and/or over-rotate to compensate for the short backswing.
As a last-ditch effort (that you may as well try), you may try hitting without closing your shoulders, and instead swing from neutral to semi-open shoulders making contact the same way Wawrinka does (semi-open). But note that even Wawrinka closes his shoulders on the backswing. You'll probably have to muscle the ball more, also.
Sadly, moving to a 2hbh may be your best option. You can hit the 2hbh both open and neutral, though neutral would probably be preferred if you had the time to set up. Agassi seemed to like to hit neutral and he did it very well.
With a 2hbh, you won't have to close your shoulders as much as the 1hbh on the backswing. Also, you will be opening your shoulders up more on the forward swing and will be making contact more to the left of your body instead of your right. All this should help you get a better look at the incoming ball. Lastly, the later contact on the 2hbh will give you a split second more to adjust to misreads of the ball.
So even if you hit the 2hbh from a closed stance you're likely to get a better look with a 2hbh. And of course the two hands will allow you to further adjust to surprises.
You should probably start learning the 2hbh using a closed stance, then hit open and neutral shortly after. The easiest set up would probably be to keep your left arm straight and right arm bent. Be sure to transfer your weight fully forward on neutral/closed-stance shots, like you would with your 1hbh.
I does copy Wawrinka a lot. He open up his body a lot when hitting. I open up too mostly because I lost track of the ball when turning and just want to regain the track of the ball by opening up earlier. It's OK to deal with slow or medium paced ball, but when the incoming ball a bit faster, I start to loose track of the ball right before the ball come into the hitting zone(that's the time I need turn further closed I guess). Basically I think turning the head for my 1hbh is relatively a big deal for me when the ball is faster. I would speculate a normal person will not have so much a problem which turning because the right eye can still track the ball, but I never know since I do see a lot of one-handers struggle with their backhand.
Good explanation for those advantage of 2hbh. Those points really make sense to me. It seems very promising to fix my problem. I just have to make a hard decision before I really do it... I have tried 2hbh a little bit, very awkward for me. Miss hit, hard to generate the power is the least to say. But it's good to block high and further ball. I think I have to bite the bullet one day...