" Hardrock and Wasatch probably do scare off the road guys because they are super gnarly courses. Running 100 miles in 12 hours on a track is a hell of a lot different than running 100 miles up and down mountains in 20+ hours. Do you think that a 2:05 guy couldn't train with specificity and then win them? Obviously they need specific training, but do you think there is something specific that you have that a 2:05 guy couldn't develop in addition to his insane fitness? "
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A 2:05 Marathon runner developed his speed over years and is now on his high of his career which last maybe another 2-3 years. After that he is burned out.
A Karl Meltzer, for example is not the fastest guy on the planet but exactly the right guy for the Hardrock 100 course where running fast is not exactly what you need. You need to navigate through difficult terrain over a lot of 13.000ft passes, you have wet feet all the time run over a 14.000 ft peak and that through day and night with no pace car in front of you, no crowds just a couple of goats here and there.
"Insane fitness" alone does not help you too much on a course like this.
Ryan Hall is specialized on fast Marathons and Karl Meltzer is specialized on trail 100 mile races and most likely both of them will never be in the same race.