This isn't a callout in any way to you, but really just a placeholder for this topic.
You will see a lot of instances of players wide open that the QB never gets to and there's a good reason for that; the player wasn't in the progression yet.
As a QB, you have certain reads on every play. Generally, it goes like this:
1. Presnap read, where you're looking for a certain placement on the outside, be it press man with no safety shade etc. If you get that look, it's automatic a shot to that receiver.
2. Post-snap read, where you go through progressions. If you have a read and that player is open, you're going to throw it there. If the backside read doesn't even have a player cover him, you'll never throw it there because you won't even look at it.
3. Second-read, normally some sort of combination off the first read, where if this look is given to first read, you know to get to your second read.
4. Third-read or scramble. For most QB's the third read is a checkdown or a scramble.
5. Backside, this is normally only seen if it's an alert or a scramble play. Generally, you're using that backside receiver as some sort of clearout or hold for the safety to play off of him. If he was in the progression, he'd be a read.
What you see on so many of these wide open replays that the QB missed is simply because the coverage messed up on a clearout route that's not part of the progression and not really a mistake by the QB. It's really only a mistake if the QB didn't come off other reads that weren't open.
Restrepo was open, just not uncovered open, so he was the correct throw with that progression.