This is the age of precision matching of frame weight, balance, grip, swing weight, tension and blah blah blah. In the 70's it was common for players to alternate between totally different racquets from one week to the next. For instance, Newcombe played with an all metal Rawlings Tie Breaker in the US and won at Forest Hills in 73 , yet when he played in Australia or the UK the same year he used Slazenger woodies winning the AO in Jan 75. Rosewall, Laver, Roche and others had similar contactual obligations meaning they had to alternate between wood and metal. BJK made the Wimbledon final with a T2000 in 69 and subsequently went back to Bancroft woodies in the years that followed. Hitting with a T2000 compared to a Dunlop Maxply is a completely different experience. I cant imagine a modern day pro being able to successfully switch between two such different sticks. Is that because the game is more professional now or because the modern day player relies on equipment much more now that in the past? Or some other reason?