I am working on my stance and pre-shot routine and I discovered something that you ought to try.
I have been paying attention to my heel position lately and making sure my feet were fully flat on the floor. This really helped. What I notice is that the cue ball is crisp and the object ball flies into the pocket.
There is a natural tendency to extend the back foot and in the process, not pay too much attention to the relative position of the heel in the process. Try it. Keeping your rear leg fairly straight but not locked in position, place the heel of this foot on the ground. You should feel a stretch down the outer part of your rear-leg calf muscle.
At the master level it is all about contact. You can make balls but if your object ball is sliding or bobbling into the pocket it suggest a poor contact with the cue ball. Your sighting on the object ball has caused some of you to connect with more purity on the object ball.
You are seeing some nice shots going into the middle of the pocket. Now I want you to FEEL THE HEEL. and make sure your feet are flat and solid on the floor before you deliver the stroke. When you get back up from your stance, push yourself up with your right hand. Do not use your back muscles to return to the standing position.