Suppose you have two guys. One is built like a linebacker and runs an 11 flat 100m. The other has the BMI of Kiprop and runs a 30:00 10K. Both of them are best at their respective events. The sprinter's 200m and up times are worse than his 100 time, and the distance guy's 5K and below times are worse than his 10K time.
Which is easier, getting the sprinter to run a sub 5 1500, or getting the distance guy to run a sub 12.5 100?