As the sport gets more physical, USTA head of development Patrick McEnroe says 98 percent of aspiring pros could benefit from playing college tennis.

That has increased from 90 percent when he took the job in 2008, he told The Atlanta Journal-Constitution.

"Unless it’s a given that you will be a Top 20 player, and you never know that, I think college is a great place to go and mature physically, emotionally,” he said. “There’s great coaching, great facilities. I think the competition is coming back to where it’s getting better and better.”

Two of the top three Americans, including world No. 12 John Isner, completed in college before going out on tour. Some players play for a school for a year or two before turning professional, instead of playing all four years.

With the average age of the Top 100 now more than 28 years old, players who receive the benefits of college training and coaching are well-positioned when they start playing professionally. That is the new assessment of just-elected Hall of Fame coach Nick Bollettieri, once well-known for producing teen phenoms.

"The physical make-up of the game makes it difficult for a young boy graduating high school, being a professional player and making it without injury," he said.