Proof that ultras are hard

When I was in college I ran 28:50's and 13:40's for 10k/5k. The year after I graduated I was training about half as intense (which is still way more than most people), still thought I was fast. Decided to run a track 10k and ended up running 30:30, a far cry from what I was a year earlier... If you don't do the training, you're not going to run fast. Just because someone was an olympian a decade ago doesn't mean they're still fast. A 2:10 person from a decade ago could only be a 2:35 person now, or even worse. Depends how much they are training.

Running 100 miles on a hot day on tough terrain simply requires a different skillset than running 5 minute pace for 26.2. Sierre-Zinal, loads of 2:10-2:12 guys blow up on the climbs. It's not that elite marathoners can't hack it on the trail/ultra scene, it's that the training required is different. I would imagine if you are running a sub 16 hour WS, you probably aren't needing to power hike too much, but you are still out there almost 8 times as long as a marathon. Plus if you blow up in a marathon at 2:10 pace, you might still finish in 2:20. That would be almost an hour and a half difference at WS for a 16 hour finish. Plus you have to factor in nutrition, and handling technical climbs and descents (Western is a tough course, but it is "runnable" for elites).

Runners typically can finish Western States in about 6-7.6 (Average of about 6.4) times their marathon best time, though, there isn't much of a correlation.
For example, a 2:30 marathoner could run between 15 hours and 19 hours. It is really hard to guess without prior trail/ultra results.

Sage Canaday can elaborate more on specificity of training.

Besides Walmsley, sub 2:20 guys have never fared that well at WS. Michael Aish, King, Wardian, Sage...

And it took Walmsley 3 attempts before he won.

There are numerous athletes who could conceivably run sub-2:10 in the marathon but who remain undiscovered because they have other priorities, would get injured training enough mpw, etc. The same is true at lots of distances. Commitment, resilience, and mental endurance are types of talents and skills, even if not quite as rare unto themselves as pure speed. And for those who consider the ultra talent pool to be ultra-thinned-out: Sure, there’s less monetary incentive to win ultras, so that will thin the pool, but the same is true about distance running relative to many other sports. Champs are champs, and eventually enough people take a sport up to give its results cachet. Ultras have reached that point, … and the nattering nabobs of no endurance can go drop some sub-14 hr 100-milers if they disagree.

Has anyone said that ultras are easy? I don’t know that anyone claimed that. No one with a brain anyway. People have claimed, however, that it takes less real physical talent to do a world class ultra than, say, a world class 10K.

That said, the ability to shuffle along steadily for six or eight hours is, in and of itself, a fairly rare genetic capability. So maybe at the highest levels the athletes are very talented in their own way.