Sometimes, a coach is enough. But sometimes, a player needs an extra boost from someone who is not a coach, but a mentor. Marion Bartoli, who just won Wimbledon, is an example. She engaged 2006 Wimbledon champion Amelie Mauresmo to advise her, and what Mauresmo did--to put it in simple terms--was to tell Bartoli to lighten up and chill out. So instead of doing drills before the final, 2013 Wimbledon champion was singing and dancing in the locker room. It may have been exactly what she needed.
Consider Kirsten Flipkens. Her career was almost ruined by injury and illness, and--she says--almost everyone gave up on her. But not longtime friend Kim Clijsters. After Flipkens suffered a blood clot scare, Clijsters took it upon herself to become a mentor and advisor. Flipkens' career turned around almost instantly, and she made it to the Wimbledon semifinals.
In 2010, Francesca Schiavone asked Italian Fed Cup coach Carrado Barazzutti to accompany her as her coach at the French Open. And while I'm sure his coaching was sound, and then some, there's also reason to believe that Schiavone was clever in attracting a Fed Cup atmosphere to her French Open effort. (More than one of us used to say that at every big event, someone should hit Fed Cup Queen Flavia Pennetta on the head, and when she wakes up, tell her she's at Fed Cup.) Barazzutti's presence represented a spirit which had led Italy to Fed Cup victory, and from which Schiavone no doubt benefited in Paris.
Martina Navratilova was asked by Arantxa Sanchez Vicario--who "discovered" Svetlana Kuznetsova--to take a look at the talented young Russian. Navritalova made Kuznetsova her doubles partner, and she told her: "I won the U.S. Open, and you can, too!" And she did.
Sometimes a coach is enough. Sometimes, a "mental coach" (the term used by Schiavone for a sports psychologist) is needed. And sometimes, a mentor who comes along at the right time is exactly who a player needs in order to break through to another level.