Getting a "mental coach" appears to have helped 2014 Wimbledon champion Petra Kvitova regain her mojo in a big way. Francesca Schiavone, who lost in final after final, sought the services of a mental coach and won the French Open.
"Mental coaching" is apparently the relatively new euphemism for "sports psychology." There are some players (Aga Radwanska jumps immediately to mind) who are too--what?--misinformed, insecure, out of touch--whatever--to see a sports psychologist, though it would do them a world of good (and why aren't their coaches insisting on it?). Perhaps calling sports mental health experts "coaches" makes it easier for players to accept the help. I don't know.
What I do know--because I pay attention--is that regular coaches sometimes are not up to the task of dealing with their charges' fragile psyches. My educated guess is that they try to help, but perhaps don't know enough to offer the kind of help that players need. That's not a criticism--a tennis coach is supposed to understand mental and emotional goings-on, but only up to a point.
I have never met a sports psychologist or "mental coach" so I don't know exactly what it is that they do. As a very experienced psychotherapist, I know what I would do, and I wish I had the opportunity to treat--oops, coach--athletes. Here are some things I would bear in mind:
Some athletes, though their ability indicates that they should have belief, don't believe in themselves because of the way they were treated as children. Not everyone with talent can be a Steffi Graf or a Mary Pierce and overcome the sins of their parents.
Becoming a famous or fairly famous athlete means that people are going to say all kinds of things about you, most of which are untrue and some of which are very cruel. You have to be taught how to handle that, just as you have to be taught how to handle the "good" celebrity attention.
The more accomplished a woman is in sport, the more sexist and misogynistic the attacks against her become. The past few generations (at least in my country) have pretty much ignored bigotry toward women, so a certain degree of gender self-esteem may have to be learned.
Left-handed athletes are known to have an advantage in many sports, including tennis, but left-handed people have some disadvantages, too. Leftys are more prone to have fearful feelings and to worry and obsess about negative thoughts. When we see a player like Kvitova, an extreme talent who is also known as a "head case," we are probably looking at a brain hemisphere issue. If I were Kvitova's "mental coach," she'd be doing Tai Chi and/or Qi Gong every day to balance her left and right brain hemispheres. It can make a big difference.
Athletes have other mental health issues, such as anxiety disorders and depression, and those need to be addressed.
Hypnotherapy is very useful in changing a player's belief about everything from her serve to her ability to close matches. It would seem to me that hypnotherapy would be a standard intervention in sports psychology.