Muscle memory isnt something thats easy to build up. I have as much problem building up muscle speed and strength than I have understanding complex riffs. Both deserve, IMO, plenty of credit, and to acquire muscle speed and strength like Alex, all the Jazz players have alot of practicing to do. Sure they will understand the riffs and composition straight away, but I dont think they'll be able to play the song right after hearing it once. They'd have to practice for some hours to get it down, if not days to build up the muscle correctly.
Thats all I'm pointing out. The fact that Jazz players can easily figure out how to play this or that is besides the point.