So this is Victor's RRI explanation: Is it just me or are they intentionally trying to make it obscure? So Stiff Response would result in "efficient transfer of power to the shuttlecock" while Flexible Response would "require less energy to be used"? What? Wouldn't an "efficient transfer of power to the shuttlecock" result in "less energy to be used" For example: Two rackets with the same shaft stiffness and balance have a three level difference in response...What does it all mean?
I look at it like compact explosive swing with forearm vs longer windup swing with shoulder. Eg. Jung JaeSung with MX80 vs Kim HaNa with BS12.
It's all marketing with little science. For instance, in materials science ductility refers to how a material permanently deforms. Obviously this doesn't happen for racquets, besides carbon-fibre composites are the opposite - the are brittle and break instead of straining when stressed past the yield point. Instead all racquets operate in the range of elastic deformation, the amount of which is described by the stiffness. These are all first year engineering terms, and if they can't even use them properly the rest of their information is probably quite unreliable too.
