In my opinion it is essential, and in this video that takes Roger Federer as an example, we see how the change is important not just for marketing.
Many people forgot the first Federer and his attitudes, when he still did not constantly rely on a mental coach, and sometimes he had very rebellious character that prevented him from expressing himself at his best, taking out the worst of himself.
In this video you can extrapolate how essential it is to work a lot on the mind because we need to focus our energies in the right direction....we need use the energies to help us and not for destroyng our match, results...
If you'd like to be strong you have to focus on your mind too and not only on your body and shots.
You have to change your bad attitudes if these attitudes can take off the "right" energies ....
The mental challenges often begin with pre-match anxiety. They continue with various emotional ups and downs during the match, like going from a bad mood, losing focus and feeling frustrated ... to being anxious, nervous and angry.
Players "lose" themselves in the emotional storms of the mind and play tennis well below their potential.
Maybe if Roger Federer had never supported a mental coach, today he would be like a Paire, or the opposite, think of a Paire or Kyrgios with a mental improvement so strong what they could do.
As always, I wish you good vision and good tennis and if you want, I await your opinions.