I imagine it had to be a little knee shaking to commit to going full hollow body in the Pro model for the design team.
i'll get the exact quote wrong, but i recall in our meeting with callaway's design team at the 2019 grandaddy, doc hoc said something to the effect of "we won't make a hollowbody iron just to make a hollowbody iron. we'll make a hollowbody iron when there's a reason to make a hollowbody iron." that's pretty encouraging. it tells me they put a lot of thought and design and purpose into this model, so i'm excited to try it and learn more.