Let me ask you all this: if you were Webb, and if you had been clean your entire career and then started dropping performances like these, would you not get yourself checked out thoroughly for mono, mitochondriosis, lyme disease, or whatever?
I would try to find some physiologic explanation if I could, and if I did, I would make it public (unless it was venereal), and possibly medicate in order to heal.
Failing that, I'd train so F-ing hard that I would either succeed, or destroy my body trying.
He doesn't appear to have any training-related injuries right now, so IMHO it is reasonable to conclude either that he has some sort of illness that he doesn't want to talk about, or that he has lost it mentally and doesn't want to or is unable to acknowledge that he should move on with his life, or both.
Too bad, I know he has been a model for other mile-type guys out there.
In any case, he's fighting something internal--and when an athlete is fighting against something within himself rather than fighting against other competitors on the track, he will not win an event that is not based on pure ability.
I'm no miler, but I understand that it can be a very tactical race, with thinking, and team tactics possibly involved. In that environment, there is no way that you can win if you are battling yourself. Total focus needs to be had on the race, not on your own demons.
What types of things has he been talking about post-race? Has he been talking about himself, about his internal state, about his health, about his training, etc., or has he been talking about external things, like getting boxed in, the race dynamics, positioning, elbows, and the home straight?
If he's talking about internal things, the suggestion that he is finished is supported, IMHO.