I can't imagine anything so challenging as dealing with anxiety in a very public way, as he did. Any failures he had were out there for everyone to see, and trying to learn to forgive himself for any shortcomings seem almost impossible when there are booing fans, critical sports writers, and other players standing in line for his job.
For a long time, R. A. Dickey took the mound already on the defensive - with a prayer that everything would go okay, and that he wouldn't get "beat up" out there. He was going about his business from a place of fear, hoping for enough blessing to get by, and chastising himself whenever it didn't happen. His journey took the better part of ten years, but the story is enlightening. And there was a lot of wisdom in the book pertaining to more than baseball.
First, sometimes trying harder is not the answer. I think it goes without saying that life requires effort, and skills need to be practiced and developed. But after a certain point, it's going to have the opposite effect in that it takes away from the joy and satisfaction you should be experiencing in what you're doing.
Second, concentrate on controlling what you can control. We can't always dictate the outcome of our efforts, but we can make doing our best, and being "completely in" whatever we do, our goal. And in that, we can succeed. Do the very best you can, enjoy it to the fullest, and leave the outcome to God.
Thirdly, and I think most importantly, is that fear knocks on everyone's door. As with most uninvited guests, if we open that door, let it in, and make it feel at home, it'll be back frequently. Dickey uses the analogy of birds of prey circling overhead - we see them, we can acknowledge their presence, but we don't need to let them build a nest.
There's a lot more to this book than the little bit I've touched on here, and it's a great story. Seeing how Dickey's faith increases and unfolds, as well as seeing him, warts and all just like the rest of us, is inspiring. This is one book I may read twice.