my theory on this is they are great at longer distances becuase they are training for those distances, like the top guys at those distances train!
Did Vigil mention recently 100mpw in HS? Great... for 10K and up! Perfect.
High milage + 1 tempo + 1 track session a week is NOT how top 800/1500m/5K train in winter. Im pretty sure Meb + Hall is doing this.... hence great times above these distances.