Dave, the average male in the U.K and U.S.A. is 5'10", 3" shorter than the average for the top male players. If you research it you'll find that the top female players are also taller than the average female. I'm a long time player in USTA leagues and experience has shown me the truth in the old saw "A good big man beats a good little man", true in tennis but maybe not so much in some other sports.
I only brought up height because Will Fly wrote "Size counts for very little in tennis" and I wasn't sure if he included height in his assessment so I thought I'd chime in.