I agree that fear enters into it, but that fear of failure came from somewhere...probably external.
What I'm saying is that words have meaning, even to softball players.
It may be "failure", but it's not an "error" or a "mistake" when giving the best effort.
Is it really a "best effort" if they aren't actually making an effort at (or near) the limits of their abilities?
Some coaches see a best effort that isn't successful, and recognize the effort as being the important factor. Some coaches only see the failure. Likewise, some players will beat themselves up over a failure, even when it's their best effort. Yes, a lot of times that internal response has been influenced by an external source (parent, coach, etc.), but it's still a real issue inside the player's head.