I found one article about this:
https://www.runnersworld.com/advanced/a20835578/the-easy-day-pace/
From the article:
"At the opposite end of the spectrum is Mo Farah, winner of two gold medals at the same Olympics where Kipyego took silver. Until last fall, Farah had been averaging 7 minutes per mile for up to 40 percent of his weekly volume. But as he was preparing for his marathon debut in London, his coach, Alberto Salazar, instructed him to speed up his easy-day pacing in order to get more benefit from all that mileage. Farah now runs much faster; with training partner Galen Rupp, he works down to 5:30 pace on easy days.
If the faster pace leaves Farah with heavy legs, Salazar doesn't sweat it; he told Running Times in March that the goal of feeling fresh for workouts is overrated. "If you're always worried about feeling perfect for every workout," he says, "you may never really get the conditioning you need." "
He was pushing 5:30 on easy days while with Salazar and now he finds 6:50 adequate? Maybe i'm not appreciating how drastic the taper was but it seems like a 2:05 guy used to grinding 5:3x's would find 6:00-6:15 quite enough of a jog. I recall Moen around ~3:40/k on his easy days in Kenya.