Just look at this workout, one of his last workouts before Boston.
He does a 5 mile “tempo” in 24:30. So he can split 24:30 in a marathon at 5,000 feet? Yeah right. That MIGHT be a tempo split if it was at sea level, but even then it’s fast.
That’s the problem, he’s trying to run workouts at 5,000 feet that sound good if he was at sea level.
He’s addicted to getting the right splits for the ‘gram. Maybe just move to sea level