I recently jumped a level or two because of the back had grip. What I discovered: finger and palm pressure during strokes. When I take my practice strokes, I focus on grip and the cue moving across my fingers and palm during the stroke. This gives me a straighter stroke and better speed control. Speed control was the biggest improvement. The best way to explain this is, when I play shape now I don't guess the speed, I feel it. For example: drawing back 2 feet. I don't think it is coming back 2 feet because I feel it is coming back 2 feet. It was a huge jump to get down on a shot and feel (believe) it is going exactly where I want. I can do so much more with potting and shape.
Changes I made.
Notice the pressure on the index finger during back stroke. This pressure helps with speed (how hard I hit it). Less pressure is easy - more is harder.
taking pressure off middle finger down to little finger during back stroke. (allows for more power and longer stroke while keeping level cue)
putting pressure back on these above fingers to make up the difference in speed lost during OB contact. what I am saying here is I take a stroke to roll the CB 3 feet. with a full ball hit I still focus on the 3 feet and put more pressure on those fingers to make the stroke harder. I feel that stroke stays the same speed and the wrist and fingers make the difference.
Finish in the pocket. I have a place my hand finishes. Hard or easy, long or short stroke, I try to finish my hand at the same place. Gives me the same finish on tough or easy shots.
Anyways, I could probably do a little video that would explain it better.
Hope this helps