Two things. The first study referred to essentially took the research undertaken by others to parrot their claims. It is basically a recitation of Nike's sales pitch. Hence:
"The most comprehensive studies have been conducted based on the Vaporflys. Nike’s claim that the shoes allow for the 4% improvement in the running economy was confirmed (here and here). Translated to running performance, this means 2-3% better finish times."
Second point: if that claim is going to be accepted then that means El G, Lagat, Ngeny and Morceli among others would have experienced a 2-3% performance gain on their best times. That is several seconds faster than the times they achieved over the 1500/mile. That makes them way faster than the best today using those shoes. It is an unavoidable conclusion from what the "research" above claims.
The study makes no claim that the shoes favour less efficient runners more. It indicates they work best with trained elites. So 5 seconds gain over a mile for a college athlete will be correspondingly reflected in the performance of top athletes.
On the issue of running economy (RE), the subject of the second paper, the question is not whether RE contributes to performance but the extent that it does so and then the contribution of the factors referred to in the study, and in particular the shoes. The conclusion about how much the shoes might improve performance is still only an estimate. It isn't definitive. It can't be, because there are so many variables that must be taken account of in calculating the effect on performance of one kind of shoe over another. That is why the subject is still being debated, including on this site. Most claims being made are anecdotal and not research based.
