We all rally around how insanely deep the 1500 (and 5000) are this year. A bunch of people running under 3.30 in several diamond league races. Huge PBs and NRs are common all over the world. Age records among teens are set every month.
Is it the shoes? Is it the track? Is it the training?
No. It's their heads.
This is the mindset of a good runner:
"If everybody else is running 3.29, why cant I ? I train as good as them, and I am a runner of the same caliber, so i just need to get in there and follow the lead pack."
If the lead pack runs 3.35 several others will run about 3.35, if they run 3.29 i run about 3.29."
They are competing and comparing themselfes with the competitors, that's what makes them run fast. Not their physiological capability.
And far from all top runners have the mindset of a winner like Jakob. Most of them are not capable of seeing themselfes defeating Jakob. And Jakob on the other side is deeply and truly convinced that nobody in the field is capable of defeating him. He's in their heads. And since Jakob is breaking limits, and is the one (and only) doing a masterclass effort, the rest are just drafting in to great times.
For Jakob to get the WR, sub 3.26, he needs to be challenged more than he is this year. The followers (aka the other top runners) needs to close the gap even more. I think that is about to come within the next two years. This is how sport develops. This is how athletes mindsets are.