I don't think Taylors theories are always appropriate in todays game. First, I believe the thumb pitch with respect to the finger pitch is more important than the thumb pitch with respect to span. I grew up with those old standards, and have a span of 4 13/16, 4 7/8. As a result I used a 1/4 reverse for years. I also used 1/4 tuck on my fingers. When I tried to go with a softer release and not hit up with lift I had a hard time making the change. After looking at what some of the pros were doing, I went with 1/4 forward on my thumb and 1/4 away on my fingers. By doing this it shifted the weight of the ball in my hand more towards the pads of my fingers than down in my palm. For whatever reason this allowed me to keep my grip more relaxed without grabbing, and I easily cleared the ball just as early even with the forward thumb pitch. I have since gone to 1/2 away on the fingers, but made no further change on the thumb. I think the key was really the change in finger pitch for my needs.
The flexibility of your thumb can have a determination on the pitch needs. In my case I can use almost any thumb pitch from 1/8 reverse to 1/4 forward with the away finger pitches and get the release I want.
In the end it depends on what you are trying to accomplish with a pitch change. If it is a comfort issue you may need to make different change than if you are looking for something different in your release. In either case don't neglect possible finger pitch changes to accompany any thumb pitch change.
