I loved it as well. I love how Willis is always thinking about his training. When I was coaching, I'd say to my freshmen, "Ultimately, I want us to be co-coaches."
A coach can perfectly prescribe everything but ultimately we never know how you feel on a given day. We don't know if you are stressed by a relative's health (whether it's a grandparent in college or child as a pro), had to stay up late (for an exam in college or deal with a sick child as a pro), etc so it helps if the athlete understands what one is trying to accomplish on a given day/time of year.
Of course, it's a fine line as there are athletes that can over think it so trust of the actual coach is key.
And Willis clearly trusts Warhurst.
What you are seeing above is a photo from this past weekend. I happened to be in Ann Arbor for a wedding and texted Willis. He showed up the night before the wedding with Ron and the groom was thrilled as he's a former 3:41 guy.
Great guy, great career, great interview.
A Fayetteville Manlius alum - who ran 1000 miles in 10 weeks in HS - was there and was going to talk to Willis about Willis' upcoming plans to do that for the first time in his career but the FM alum got tongue tied/star struck and didn't tell him how it's done.