The pre-snap reads of the defense are not solely McVay or Goff. They are a team. The offense lines up early so McVay can give his take on the defensive setup. You can confirm this because we rarely snap it early and use a bunch of hard counts to expose potential blitzers quickly in the play clock.
However, Goff is well coached enough to act as an extension of McVay after 15 seconds and gets better at it every week. There were at least 3 occasions where he audibled late and correctly diagnosed where the blitz was coming from.
He still has room to improve though because he outsmarted himself on the intensional grounding play. He saw their was an overload blitz on the right side so he audibled Gurley to pick it up. After the snap, the pressure still got to him so he threw the check down. The only problem was, Gurley was his check down and he had changed his assignment pre-snap to blitz pickup, hahaha.
Definitely a bright young talent overall and he hasn’t neared his ceiling yet.