Forget about ... wrote:
Forget about Coe's 800m, 1000m, 1500m and one mile performances for a minute. Think about the individuals you know who went from 56.xx 400m PB at age 14 to 46.xx 400m PB at age 22. Many of us know males who made that exact time improvement from age 14 to age 22. All the men I know who made that time improvement were built like robust 5'11" to 6'3" men by age 22. Coe went from 56.xx 400m as a runt 14 year old to 46.xx as a runt 22 year old. I doubt Coe's improvement in 400m more than his improvement, 800m and longer events.
The runt is a the new paradigm. Compare the squat powerful Maurice Greene and Ben Johnson types from 80s and 90s to todays' sprinters. Now you got DeGrasse and van Neikirk, relatively slim and slight (Lemaitre is another example, not too shabby with 9.92 and 19.8 speed but injured a lot last couple of years). As for middle distance, ya coe was scrawny (possibly his East Indian heritage) but the new mid D guys like Kejelcha and of course Mo Farah are walking sticks yet with strong sprint finishes.
The Aussie and Kiwi milers from the 60s-70s were maybe "robust" as you describe, and Bannister/Landy as well, but the kiwi Zane twins are also walking sticks that were scared sh**less of playing rugby. Robust monsters like Tegenkamp and Solinsky were fun aberrations i'd say. At least that's my cherry picked data....