While training and preparation likely played a bigger role in Rupp's win and Hasay's moving to second on the US all-time list, even small changes in form can have big effects on performance, particularly over 26.2 miles. The one sentence summation I would give Gruenke's analysis is: a shorter lever is a faster lever. She has great insight into Rupp's improved arm mechanics since his bronze medal run at the Rio Olympics last year. For coaches of long-distance athletes, this is a good read.
Chicago Marathon form analysis, from The Balanced RunnerWritten by Kevin Mangan
Coaches shouldn't always copy exactly what others do, but learning about why others do what they do can be rather helpful in gaining knowledge. This is particularly true if learning from successful coaches and athletes. The Balanced Runner, from Jae Gruenke, has a great analysis of how Jordan Hasay and Galen Rupp made some form adjustments that seem to have worked quite well given their Chicago Marathon performances from a couple days ago.