My first reactive resin ball was drilled zero thumb pitch and no slug. At the time I didn't realize it, but I have been squeezing the ball for years with the reverse pitch that I had in my Brunswick LT48. Switched to a reactive ball so that I might get some hook.
The reactive ball's coverstock was a bit rough and I eventually tore up the back of my thumb due to the squeezing that I didn't need to do. Just a bad habit.
The PSO put in a slug for me and it was much better, but I was still squeezing. Next the PSO gave me some protective HADA tape to see if that would help and, of course, it helped a bunch.
It wasn't until I asked the PSO to redrill for forward thumb pitch and began to experiment with a tiered tape on the front of the thumb hole that I started to keep my thumb much straighter to clear the hole.
Unfortunately it took me quite a while to retrain myself to get away from a full roller, squeezing and muscling the ball down the alley to actually allowing the ball to come of my hand cleanly and get a few revs on it. Things get better if you work at it and find yourself a good coach to work with.