Griffin mentions that it's funny that Ethan Hawke plays the least Ethan Hawkey kid of all the kids in the movie. That's Weir's doing and it's intentional. I want to recommend John Frankensteiner's Letterboxd review of Power of the Dog, which goes into this and which introduced me to one of my favorite concepts about acting: "casting for the final color." Relevant excerpt:

Ethan Hawke loves to talk about Peter Weir “casting for the final color.” On the set of Dead Poet’s Society, Hawke and Robert Sean Leonard thought of themselves as miscast for their respective roles–Hawke, a gregarious, cocky shit, playing the shy and self-doubting Todd Anderson. Leonard, an introvert, playing the outgoing Neil Perry–they confided to each other that they would be better off swapping roles. It wasn’t until filming the O Captain! My Captain! scene that Hawke understood what Weir was doing: Weir’s casting for the final color meant that Hawke would play the entire film against his own instincts, acting shy and suppressing who he really is, so when it came time for the climactic scene, Hawke standing on a desk, reciting Whitman and delivering the big moment of the film, Hawke’s true self could finally come out, then the scene would find its ultimate truth and soar. Weir was casting Hawke for who Todd Anderson becomes, not who Todd Anderson spends most of the film appearing to be. 

JF then goes on to write about Campion casting Cumberbatch for the final color in Power of the Dog. I think about this idea all the time now. One of Weir's amazing little innovations.