"When we developed the original power formula in HBD, Bonds was hitting 73 HR / season. All our data and formulas were based on a time period that is no longer valid in the MLB, so we brought the upper end down. The change we put in place only impacts the upper echelon of HR hitters and only impacts HR. We, and many users, did not like seeing players blast 70,80,90 HR in a season."
I think it's reasonable to assume, while tinkering to make HR totals less, they over punished the elite power hitters.