it's more that the guys "tightened up" the laps in the distance races from '90s onwards
the likes of viren/pre/puttemans/maybe quax, dixon shouda gone 13'00 - 13'10 in '70s ( maybe more like 13'05 - 13'10 ) but they had such poor pre-conceived ideas of what pace to aim for
these guys were animals & shouda had no problem running 5k ( mabe 10k ) to their potential
pre ran a ?solo 27'43 on a windy day in eugene in '74 - probably worth well below 27'40 on windless & maybe below 27'30 with pacing to 1/2 way
he had 3'54 speed from year before - maybe lot better if he'd run it few times ideally ( but then again '74 maya been shift to endurance )
i'd offer him a prelim for '74 of
52.5 / 1'50.7 ->
3'37.3
3'54.3
7'35.9
13'06.1
27'23.4
the latter 2 wouda been huge wrs in '74
( moreso the 5k as it was 13'13.0 from emiel, less the 10k which was bedford's 27'30
( remembering viren's '72 win when he ran 27'38 in which he fell down - probably close to 27'20 that day in a paced circuit race )
worth noting though, puttemans 8'13.2i wr in '73 maya been an intrinsic ~ 7'30/7'31 outdoor effort !!!
ovett only ran 8'13.51wr outdoors to beat rono in '78 ))
a lot of wrs in '80s, then especially '90s on were due to realising that each lap has to be run brutally hard