Few players do less to hide their emotions: when Pontus Jansson is happy, he runs to the fans and punches the air, and when he's sad, he turns his entire face upside down and glooms away down the tunnel. If there's any doubt how he's feeling, there will be an Instagram post explaining it.
Bielsa sits, crouches or prowls, eyes on the action, with one aim in mind that inspires countless thoughts and strategies: get this plan working. Bielsa has one way to play. His flexibility comes from the extraordinary lengths he'll stretch to so that he doesn't have to change a thing.
At times you could feel the strain Leeds' players were under; it would have been easy to revert to last season's type, to concede a stupid goal, have a couple of players sent off, give it loads of bollocks in the second half when it was too late then end up losing amid boos. But that was then.
Tthere's something simple and appealing about Bielsa's stoic-ball. 'Don't worry about them, let them worry about you' is a trope that has always been interpreted by Warnockian centre-halves to mean 'kick the other bastards first', but what Bielsa offers is something more profound.
It was a battle to recapture the carefree spirit of the first half an hour, and it's Bielsa's permanent battle in sport; he intends to take not worrying about the opposition to its logical conclusion, so that whatever they're doing, his team keeps playing the same.
Frank Lampard has perfected the in-game suit, the respectful soundbite, and the pensive touchline stance; as Bielsa beamed kindly at him at full-time, like a vet about to do what's best for Lampard's favourite pet, Frank looked shocked.
United's triple-action coaching, three t-shirted tenors taking cues from their conductor and delivering an opera of instructions to all parts of the pitch, was augmented by a claque of coaches strung across the front of the East Stand, so that the word of God was heard all across the field.
Why, after watching so many hours of Liam Cooper kicking a football, does he not shudder like we do when it happens? When he lies awake in bed, in his office, thinking about Kalvin Phillips, what do his thoughts reveal to him, that our eyes, after watching Phillips for two seasons, have not?
Football is exactly as simple and complex as love, and with the right gestures, a whiteboard, and a rudimentary glossary of football terms, it's not beyond the wit of Bielsa to explain to Kalvin Phillips what is in his heart.
Marcelo Bielsa's Newell's looked closer to Howard Wilkinson's Leeds than to Pep Guardiola's Manchester City: a team hard working individuals who, by dedicating themselves to each other and to a tactical plan, achieved much more than they ever could apart.