You are misunderstanding me. I wasn't referring to looking off the safety as being a weird way to play football.
I was specifically referring to the idea of taking in everything with peripheral vision ONLY, as opposed to scanning the field.
I'm not disputing that QB's manipulate defenders, because they do. But their cognition is not necessarily locked into the direction their head is turned.
Also, I sincerely doubt safeties actually see the QB's actual eyes, as opposed to the direction their helmet faces.
Here's what it looks like to me.
1) The playcall has multiple deep routes and Tua knows where they are all going.
2) Tua sees the safety inside the left hash mark, and expects an opportunity on the left in the deep part of the field.
3) Post snap, Tua is looking right, making sure the safety is staying in the middle of the field where he can't help deep left. He also sees in his peripheral vision the WR and CB going deep left . Maybe he even sees that Smith has beaten his man this way. I doubted this at first, but I now accept that it is possible. These guys get a lot of practice and know what it looks like.
4) Tua turns his head, his vision, and attention, toward the left, giving him a chance to confirm what he may have seen earlier, and throws the pass on target. This accuracy would not be feasible with peripheral vision only. If the corner had stayed with Smith, or had forced him out of bounds, or some other thing like that, I don't think Tua throws the ball there, and I don't think he throws left without at least looking left first.