The more I see of the Feel Tennis site the more I like it.
I know nothing about coaching tennis, but I've spent some time teaching languages, and some of what he says resonates with my experiences as a teacher.
For example this article on responding to mistakes: http://www.feeltennis.net/how-to-be-...kes-in-tennis/
I try to get across to my students that mistakes are okay, that they are a natural and inevitable part of learning, that they are actually essential to learning, and that they can be signs of progress. But that idea is a hard sell (in part because the grade-and test-centered nature of for-credit classroom instruction encourages a focus on mistake avoidance--maybe this is comparable to an overemphasis on competitive results in tennis instruction).
From what I've seen the students who combine a willingness to make mistakes with a fervent desire to improve are the ones who get the furthest. Maybe that applies to tennis as well...