Agree w/poster above re: WR due more to a great coach and a returning veteran star-studded lineup that set the CR last year.
Teare's anchor split was less than a second faster than his split on last year's 9:24 team, so the Air Zoom shoes had little effect on his performance. He's just become a great college miler.
Also note that nothing spectacular was run in the distance races at the Karlsruhe meet today -- and those were pros who some/all should have had access to supershoe spikes.
I do agree with the two points Rojo stated above re: Covid Effect and believe a 3rd can be added: many college distance runners around the country have been living together at altitude for much of the fall and into the winter while taking online classes. Thus, you stay at home online & study, go out for training, come back and eat, then go to bed. Rinse & repeat.
Essentially, a lot of these runners were living the life of a semi-professional living at altitude w/school work replacing a part-time job. And, no stress of having to prepare for a race every other weekend. This environment appears to be much more conducive to optimal training than having to race around campus all day, squeeze in a team workout, then go back to the dorm and study until midnight or later.
In any case, this DMR record is just a continuation of fantastic performance we have seen since, I would say, last May when Leo Daschbach broke 4 in the Quarantine Classico Mile. Huge prs and all sorts of world & national records have been set at every level since then.