And of the two, more on McVay.
Design plays where AR is the first read on quick openers and see how things go from there. Spread the ball around... it's an old concept and begins with play design, QB decision depending on many things from there.
What it often look like to me (and I could be way, way, wrong) is that the plays called later in the game reflect McVay's knee-jerk response to go to Kupp first - and that's all Stafford has time for. The slow-developing plays usually go to Kupp anyway as he can dependably get open and has that uncanny connection with Stafford.