I remember the name Donovan Brazier when he ran 4:07 in high school and wondered why he was in more mile races. He never trained for the 1500m/mile or cross country...yet he also posted a sub 15:10 x-country 5km. Donovan will never be a 44.9 400m man but he doea have good speed for an 800m runner and great speed for a 1500m specialist combine with uncanny endurance of low mileage.
Donovan jyst like Ajee will never hold the 800m or 1500m WR but can be world threats in either event. If they focused their training on the 1500m (while in their prime) I think both will be better at the meteric mile then they will ever be at 800m. It will also might vastly improve their 800m tactics, pb, and ways they can run the shorter event.
Capabilities with several 1500m yrs training:
D. Brazier 3:28.2
A. Wilson 3:55.4