Thank you for the link, Hodge! I've written elsewhere how I got better by slowing down. Two interesting points for me are
1. He takes off a day a week. The Djiboutians did this too (running a relatively slow) 50 k/day on the days they didn't take off. For them it was for religious reasons. It sounds like Mutai takes Sunday off so he can spend it fully with his family. Regardless, maybe that day off is important. Ryan Hall is, I think, taking a day per week off too, and he hasn't lost anything (although the rumor is he's injured now...) Anyway..
2. I slowed down to 8 minute pace, but ran around 25 minutes slower in the marathon. Maybe I should have run even slower! On the other hand, I remember running for a week on the North Rim, which is at about the same altitude. I was in 2:35 shape or so at the time. As long as I was running on the flat, 8 minute pace was an easy effort (as measured by HR). When I took runs down into the canyon, though, I had to walk most of the way back up. Hills just killed me at that altitude. And I can't imagine doing anything fast - even marathon pace. I would say that Mutai's training is sufficiently intense aerobically. But it's easy on his muscles and bones. This is probably the great advantage of altitude. One can improve by stimulating change at the cellular level (mitochondria etc.) without stressing the musco-skeletal system too much.
And this guy is going to run 2:02 before he's done. Whatever he's selling, I'm buying.