The way the race unfolded, it looks like most of the world's elite marathoners don't know how to train for the marathon. After all, at least in the men's race, they all ran slower the second half of the race. All but one or two of them folded over the last few miles when the pace picked up. I see this happen time and again, even in races like the Olympics and World Marathon Majors. You might get one or two guys who are still running really fast at the end, but for the most part, these guys come staggering in like they're, uh, finishing a marathon or something.
And have you ever noticed that it's the guys who are running fastest over the last few miles who always seem to win? That provides further evidence that everybody else trained wrong. What the other guys need to do is train differently, and start training to run a marathon at a hard pace with a really fast last few miles. THAT is how you should train. All these guys who train to run a positive split, and to bonk the last few miles, will never amount to anything. If your coach tells you to run the first 18 miles at sub 5:00 pace, and then gradually fall apart over the last 8 miles, you tell him, "No way coach - that's not how marathons are won!"
I say we put the OP in charge of training all elite US marathoners.