I knew nothing about strings before I found this site. I played as a junior for years with full beds of POSG or natural gut. I beat a lot of people, but I will say that I am a better player now.
If you are using full poly and he is using syn gut or natural gut then that is a reason he never switches. But how are you a 4.5 getting double bagled over and over by a guy who doesn't ever break strings?