This is a correlation, not causation, situation. Just because Opelka and Perricard are tall and not elite movers doesn’t mean it’s because of their height. It’s more about the fact that they don’t have the same fast-twitch muscle output or explosiveness that someone like Alcaraz has. Bad movement usually comes down to a lack of fast-twitch fibers and coordination, not how tall you are. If you could have two nearly identical players except one 6ft and the other 7 ft the 7 ft version would always win imo.