Compare this with the Olympic and World Championship podiums for the 2000s and 2010s; I don't believe a non-East-African-born athlete won a single 5000/10000m medal for 20 years straight.
Jakob Ingebretsen was the other who likely could have beaten it, but he's also been hit by a fair number of Achilles issues, including undergoing surgery this past year.
Kerr's performance was very impressive, and, as he continually reiterates, the team he assembled is what led to it aside from his potential and dedication. He set a PR of 2.68 seconds (two years ago) and before that his closest time was 6.61 seconds away. Granted the mile isn't run frequently, but his 1500m times last year weren't very indicative of hitting the WR either - but also goes to show middle distance and up is often run to win as opposed to set your fastest time similar to shorter distances.
I'm not so sure about that. The 1500 is the equivalent race run at major championships (and most paced time trials). But that record (3:26.00 by Hicham El Guerrouj) has stood one year longer, and is generally considered a stronger record. This is possibly the closest anyone's ever come to an equivalent performance to the 1500 record, in either the mile or the 1500. The second-fastest 1500m time ever is 3:26.34 by Bernard Lagat in 2001. The World Athletics scoring tables value a 3:42.66 at about 3:26.3, eyeballing the midpoint of given values. (Or taking the WA point values on the top lists, Josh Kerr's new mile record is 1298, Lagat's second-best 1500m is 1297, and El Guerrouj's 3:26.00 is 1302.)
I don't know whether the WA points or other conversion methods actually have small enough error bars to distinguish between the Lagat and Kerr performances, but the 1500 record beats the mile record by a big enough margin that I don't think we need to worry about that.
https://worldathletics.org/records/all-time-toplists/middlel...
https://worldathletics.org/records/all-time-toplists/middlel...
Kerr ran an average of 13.837/100m. If the 5% rule is truly accurate (which is unlikely), there's some scope for faster times. Personally I'd bet the 5% is just a handy rule of thumb that doesn't do much more than to indicate that these are incredible athletes operating at the absolute peak of human performance.