What your buds do not understand is how heavy of a ball the guys hit. I remember a few years back J Mac/Steffi played Serena/??? in Wimbledon mixed and Mac hit her a kick serve. She got ate up by the serve and had to deflect it with her hand.
I saw Steve Bryan when he was #1 16 in Texas beat Navatrilova when she was still top 5 beat her 6-1.