I'm not the biggest Chase Daniel fan, but he is doing the best film breakdowns of QBs around. I pretty much just watch the Mahomes ones, but he points out a lot of stuff I don't see. Especially with what Reid is designing the play for.
It's important to know that as a QB, you want to split defenders when throwing in anticipation. (As show on the clip below)
I see many people in game day threads, (might be because we only get 1 broadcast camera angle) posting about Mahomes missing passes, but actually his WR's are breaking wrong angles.