idk how you can make an argument that physique is "essential" in todays football when there are so many examples that suggest otherwise, including Fagioli himself. Does it help? Sure. Is it essential though? Nah.
Anyways, just look at the first action in that highlight vs Freiburg, the back heel to Cuadrado. Fagioli is the one knocking the guy off the ball, not the other way around. He's never gonna be a guy that consistently does that though, so I think its more important that he maintains his flexibility, speed, and durability.