What is the difference between knowing who is ranked where and who has won what? Why is only the latter classed as tennis knowledge in your book? Being able to identify strengths and weaknesses of players can only really be quantified as about 5% tennis knowledge, or something, because any Tom, Dick or Harry could do that.
As I said, ATP tennis knowledge and knowledge of the sport itself are two entirely different things.
Negative Burrow. Knowing how mant Wimby's or slams Edberg won shows some tennis kowledge because it shows you have been following the game for some time, whereas anyone can find out what the current rankings is and it doesn't mean shit. Knowing strengths and weaknesses of players also shows tennis knowledge because first of all not anyone can identify them, and second not anyone is interested to. If you ever played tennis on any serious level whatsoever you would know that it's very important to know that about your opponent. So as a fan it would just be natural to identify them as well.