It wasn't the frame that was the innovation, it was the string. The Frame changed to accommodate the string. Poly was very low powered with oodles of spin, so lighter and stiffer frames allowed the player to develop RHS to accentuate the spin and yet have enough power to still drive the ball.I disagree. The development of stiff and light Pure Drivesque frames (strung with poly strings) was a game changer. You may like it or not..
I'm sure if players were still using 100% natural gut in their frames they'd be using more flexible lower powered frames