If you have trouble with getting a clean release you can try a bowling thumb sock.
I got one of each type today and I am very impressed , a great product.
There is one for when your thumb is small( thumbhole loose) and one for when the thumb is big (thumbhole tight) and one with a opening in the center to allow a bit of "feel" in the ball.
http://www.ebay.com/itm/321946411976 ( just scroll down on the page )
You are absolutely right about Thumb Sock. I don't have that but I used Hadh Patch and Turbo Skin Protection tape. I do get somewhat smoother release with those, but my questions is regarding the way thumb is inserted.
Does it have to go all the way In like in A in the picture or all the way in means upto line B.
Let's get some answers regarding that. It's very important, at least for me to know what is the correct way of inserting thumb all the way in.
My feeling as follows.
I don't have access to Tri Oval system from Jay Hawk or a mill to drill Oval Thumb hole. Hence I have always had round hole for my Oval Thumb. That makes the release very difficult. So used a lot of bevelling and as a result the thumb was being inserted way down below. There was a lot of rubbing causing a hump where it shows the callous and rough skin.
Lately, on someone's advice, I Ovalled my thumb with a Bevel Knife and filer. It felt a lot better but gripping never really stopped.
I thought the part of the problem may be too much bevelled and improper thumb hole shape