Looking beyond the completions, what strikes me is his command and manipulation of the pocket, the compact throwing motion after quick resets, and his touch/accuracy that assumes the receivers' moves at the top of the stem as he throws the receiver open. These qualities have nothing to do with score or down and distance.
I will be watching intently for the subtle variations in scheme and use of choice routes this year as McStafford more quickly adjusts in-game to how the defenses choose to attack this offense. Will Matthew absorb McVay's checks to the running game or continue to visualize passing options as that's been the necessary solution his entire career? Tom Brady struggled for more than half the season last year to implement Arians' offense before they melded AFTER the Rams picked him off twice in a loss. How long will it take Stafford to see the game from McVay's eyes? How will Sean react when Matthew sees it differently? Which receivers will he trust on critical downs? Will he stay healthy? What if the protections break down? Will he try to wing it or check it down? It's gonna be fascinating and I can't wait to see it develop.