Andy Roddick has dropped out of the top 10 in the rankings and Venus Williams has dropped out of the top 20.  Meanwhile, little sis Serena, who is returning to the tour next week in Cincinnati after several months off to rehab her knee and take a “mental break,” is now ranked out of the top 100.  Shocking news all around?  Not really… Tennis rankings reward players who play a lot and who win a lot.  Unlike team sports, there are no guaranteed prize money checks, you need to compete to collect the big bucks.  Top players do earn off-court endorsements, but those too will dry up over time without enough wins on the court.  The bottom line, Andy Roddick hasn’t played that well nor won enough matches in the past year and so frankly he deserves to be ranked where he is at the moment.  However, with a strong showing on the summer US Open Series, Roddick could boost his confidence and raise his ranking very quickly.  Venus and Serena have both battled injuries the past couple years and so they haven’t played a lot and also haven’t played that well at times.  The resulting bad losses have hurt their reputations in the locker room.  Players don’t fear the Williams sisters as much on the court these days and that can easily cost a point or two a game, especially in tight matches.  Several years ago, Andre Agassi’s ranking dropped out of the top 100 after an injury break and he managed to play himself back into the top ten and pick up a few more Grand Slam titles along the way.  So it’s definitely possible if the body is willing and the heart plays along…