My guess is that it has less to do with deflection as such and more to do with the stiffness or some other quality of the new shaft. Butts don't make a real difference, but every shaft has differing characteristics that affect the hit, including taper, tip, ferrrule, joint material and thickness. I suspect that, just like all the other adjustments you are making with this new shaft, you will simply have to allow for time for the "arm-brain" computer to catch up to this new variable. Thus, playing more with it will help.
Just as an example, many pros who have made the switch haven't been able to make a ball for months. John Schmidt said it took him a full 2 years to adjust and that, given the opportunity, he would go back and not make the decision to switch.
I personally do not think they are of supreme benefit in one pocket as their benefits typically show up in long shots hit with pace, but, of course, to each his own.
Oh, and John correctly pointed this out - if not enough deflection were the issue, you'd be hitting to much of the head ball.