Just read this months T&F News pertaining to the fact that the U.S. can't produce good marathoners. Sure we have a couple that can run under 2:10, but come on the size of the U.S. we should have many under. The article mentioned the fact that Salazar's marathoners blew up at New York.
Here is my two cents on how we can improve in the marathon. First of all, we in the U.S. have the "I want it now" , "get rich quick",mentality. I think that a runner needs to go to a college where the coach won't interval or race them to death. Work on their 5 and 10k's. Graduate from college, gradually up their mileage and begin racing 20 k's and half marathons while keeping foot speed. Then with four years of good marathon training run a marathon. Run fairly conservative for the first half then see what happens. Many expect to run 2:10 their first time out. The first one should be a good experience feeling like they could have run faster upon completion. Train for six more months and go for a good marathon. That means they won't be running all out for a marathon until age 27-28. The problem is who has that kind of patience. Ok thats my opinion.