But what doesn't make sense to me,
@Moxie, is how you can think that Roger can lose focus but not composure (choke). Both are signs of weakness of one kind or another, but why one but not the other? And I've certainly seen Roger lose composure, and his play suffer because of it.
Choking implies a certain level of ability. In baseball, it is good players who are accused of choking in critical moments - when they fail to come through when they are expected to come through. You don't say that your utility infielder chokes when he fails to drive in the winning run. Mike Trout chokes when he fails to do that, and Trout is the best player in baseball. Even though this ignores the fact that even a great hitter fails most of the time (just as in tennis, even great players lose about 45% of all points).
But again, I don't see how Roger failing to win the match when he's up 40-15 is not choking. That's the definition of choking. On the other hand, to reduce his loss to choking is to miss a lot else about the match - including how Delpo may have facilitated him choking, or how he played close enough to take it in the end. I didn't watch the match, so it is impossible for me to make a judgement about to what degree the match was about Roger choking, and to what degree it was about being out-played.
So I see "failure of form," "loss of focus" and "choking" as different shades of the same thing. They have different qualities, but the differences are smaller than we are making them. And they all are directly relative to our own expectations.