How can the MPF of older blades like TM EL-1 be greater than newer designed irons–both blade and cavity back– with all the exotic metals and engineering now available?
Good question, but an easy one to answer. The MPF is based on the mass and dimensional characteristics of the head, period. You can have all the exotics and “engineering” you want, but if the mass and dimensional characteristics of the design are not engineered correctly, the playability will not be as high. Vertical cg, Horizontal cg, Rearward cg and MOI are the key factors in determining how stable and playable (forgiving) and iron will be. Does not matter what category any particular model is in, cavity back, muscle back, etc., nor does it matter what material(s) the clubhead is made from. It is true that new materials and engineering and manufacturing techniques allow us create more complex head designs, thinner faces that can very slightly increase ball speed, and multi material designs, but if the basic principles of mass and dimensional characteristics are not optimized for any given clubhead design, the playability will suffer.