I am not a club designer and know nothing about the design process, so this question is simply trying to go inside the mind of a design process. The TS3 is so very similar to the TS1 in the design dimensions. The difference in weight, VCOG, C-Dim, and MOI may not be a discernible to me during play. Well, maybe they are, and that is the root of the inquiry. The MPF would be not be a significant difference and the lofts are identical, at least for the 6 iron. I get that the TS1 is hollow filled and the TS3 is solid. My TS1 9 iron and my TS1 PW are ever so slightly different as one is hollow filled and the other is solid, but not enough different that I care if I hit one or the other. They both feel and act as they should, compatible. I can definitely feel the difference in VCOG of the TS2 verses the TS1, but the TS3 brings the VCOG down to TS1 range. Anyone can point out the numerical differences and say, see they are different, but from a playability design process….
What job was the TS3 designed to do? When would a person find the TS3 preferable? Side by side ball hitting, interchanging the TS3 with the TS1, where would I feel it? Would the difference be in the turf interaction? Is the TS3 an improved TS2 and therefore the heir apparent? Was it designed to bump the TS2 out of the lineup someday? Take me to school please.