2-3 plays per game isn't what's important. It's the specter of the deep ball that defenses are forced to respect, every play of the game. So his ability to hit those things is pretty darn important. I'd say Tommy gives us maybe about 80% of what this offense needs in terms of ability, with the question mark being (as it would be for anyone) the mental side of things. It'd be kinda silly to expect anything other than a bevy of decision-making mistakes from any of the other young, untested QBs on the roster, though.
this is part of what's allowed Baylor to be so successful. they send a WR deep on every snap and since opposing DCs know Petty can make that throw whenever he wants, they have to scheme around it and it takes a safety out of the equation, opening up more options underneath.
Taylor had that ability with his legs. A linebacker had to spy him and it opened up the zone read or option or underneath passing routes.
Armstrong doesn't have that kind of accuracy, or at least didn't in 2013.
most of his successful deep throws were so because Bell or Enunwa made a spectacular catch.
That said, obviously I don't know if Fyfe or Stanton has that deep ball ability either.
EDIT: and if none of them do, then start Armstrong because he's got the experience. Not many guys out there can say they've led a game-winning TD drive at the Big House, and that's worth quite a bit too.