That is interesting that you mention Asafa’s arm mechanics.
In this clip where he recorded the fastest electronic split of all time 8.57 you can notice his hand goes goes well past his hip all the way through the race. Maybe this is correlated to his performance in some manner? More arm ROM at higher speeds. In his Rieti races he always seems to have good arm ROM. It makes sense that a tighter upper body would inhibit full power output elsewhere.