One of the keys is Messi’s genius. Another is the work ethic that Messi, and all the rest of Barcelona’s players, display. It is almost as if they enjoy running as much as they enjoy caressing the ball, and it is a built-in response, honed in the academy of La Masia, that the instant a Barça player loses possession, he, or the nearest player to the ball, hunts it down like a ferret.