A 5'7" man was a guy like Sam Langford, universally regarded as a top 10 boxing HW of all time. Jack Johnson ducked this guy. Meanwhile, in 2017 a 5'10 man can't even compete in a major tennis tournament. You have to look around rank 100 to find more than one under 6' guy. Why has height become so important that you can't even be an under 6' tennis player anymore?