What non Africans routinely make indents in championship races? Kincaid was the third non African. Making an indent (isn't that supposed to dent?) is an issue for distance runners that goes way beyond the US.
When you talk about choking to a massive degree relative to their potential I imagine you mean running so much slower that their best times. It was something like 90 degrees. No one is likely to run nearly as fast as they have in better conditions. But the other thing that comes into play here nearly all US distance guys with impressive times is that those times are achieved in events that are really glorified time trials. (I'm sure someone can think of exceptions but those aren't the norm.)
Championship events are actual races. Racing well requires a different skill set than simply being able to run fast and US distance running has really never been structured in a way that puts runners into settings which help develop that skill set so we consistently see what happened today, i.e. US runners with fast times in championship events running nowhere near those times and placing far from the medals.
This not anything new. If someone asked me how to change this I would say that US runners need to go to Europe and race frequently throughout July and August, to take their lumps in international races while learning how to place well eventually in such races. That's not going to happen consistently. Making it happen would require an organized effort by USATF, maybe requiring it to spend some money for it to happen. Distance running is not a high enough priority.