Here's the most thorough look at the issue of on-court coaching I've seen recently.

From The USA Today: Courtside help under fire in tennis

As second-ranked Sharapova strives to end the year at No. 1 at this week's Sony Ericsson WTA Tour Championships in Madrid, her sport is increasingly dogged by the visible pervasiveness of on-court coaching...

"Coaching goes on, and it has been abused more as an increase in money has come into the game," says Patrick McEnroe, the U.S. Davis Cup captain and a TV tennis analyst.

Most agree the practice is not as serious or results-altering as, say, a corked bat in baseball or something akin to the brown substance spotted on the pitching hand of Detroit's Kenny Rogers in last month's World Series...