Your post doesn't make much sense to me. There wasn't a sudden improvement to Ryun's record despite the introduction of modern tracks because Ryun's record was so good. At least that's what is being argued here. Jim Ryun had knocked over 2 seconds off the existing WR that had been set only the year before. To say that Bayi only shaved 0.1 seconds off it in 8 years doesn't prove that modern tracks aren't much better, or at least it doesn't disprove that Ryun's run was one of the greatest ever. Bayi was running nearly 4 seconds faster than Herb Elliott. Was he really a second lap faster than Elliott if they were in the same tracks and shoes?
Snell is considered by everybody to be in the GOAT discussion for 800m, so the fact that the two next greats only equalled it on better tracks shows what a stud he was, not that there was no difference between the tracks they ran on.
Would make more sense to compare middle-distance times from more 'ordinary' WR holders to judge if tracks made a difference. For example, John Walker ran nearly 10 seconds faster than John Landy only twenty years before. For point of reference, El G set his 3:43 WR that still stands twenty years ago. It's the equivalent of the WR for the Mile today being 3:33, ten seconds quicker than El G.
El G only improved on Walker's record by 6 seconds in twenty years, with all the benefits of EPO inside of him. In fact, many or most people here would claim that the clean WR for the Mile is probably Cram's or something like his time (ie 3:46) which is only three seconds faster than Walker's WR. So in forty years, the WR for the Mile has only improved three seconds without chemical means, and yet Walker's WR was nearly ten seconds faster than than the times of twenty years before him, and 17 seconds faster than the WR of forty years before him. I've never read of anyone even on this forum claiming that John Walker took PEDs. Obviously some of the time difference between him and earlier greats was due to better training, maybe more money coming into athletics and the gradual ending of the amateur era, but a large part of it must have been due to better tracks (as well as pacemakers and shoes).
The 800m WR progression is even more obviously influenced by tracks. Less than 7 years before Snell the WR was 1:45.7 and the record before that dated back to Rudolf Harbig in the 1930s! Yet Coe ran 1.41 less than 20 years later (and even for those who doubt Coe, Cruz got within 4/100ths of it just 3 years later). Until 1955 the WR was 1.46.6, yet by 1979 it was 1.42.3, over 4 seconds. Nearly 40 years later it's been improved by 1.4 seconds (or just 0.8 seconds from 1981 to today, and Rudisha has to be suspect like every Kenyan, unfortunately). Also, there was a lot of unusual bad luck regarding the top 800m runners of the early modern track era, which make Coe's times look even more like outliers. But a number of athletes were probably capable of sub 1:43 in the 70's and early 80s, from Wottle to Ivo Van Damme (if he had lived) and Steve Ovett. That's three seconds faster than the WR before Snell's 1:44 on grass.
