[Goose]

I could be mis-remembering, but I thought the play we ran against Oregon forced the safety to pick which receiver he was going to cover.  Costello's job there was to determine which receiver was in 1-on-1 coverage, not which receiver was uncovered.

In this case, it was really uncovered. It was one defender, two receivers. Pick your poison.
https://www.youtube.com/watch?v=0ILmr9p-bpc

Look at about 1:48 in. They "optioned" the Mike linebacker.

Your other examples are really examples of where the receiver tries to get separation from the DB (it can also be accomplished with a really fast receiver or with a play-action pass that catches the safeties cheating in on the run), but being able to get a bit of separation is not the same as being uncovered.

BC

Yes, uncovered is a "special case" of open. That is why I said most teams try to get a receiver "open". There are many different ways to do this, but it is a goal of most teams. The QB is instructed to "find the open man", not "find the single-covered man". We often throw to receivers that have no or almost no separation, i.e. are not "open". That  really puts the onus on KJ to throw a perfect ball ball. He often does, particularly when he has time. However, that is a lot to ask, and in any game, there will be mistakes or hurried throws. If the receiver is "open", a bad throw probably leads to an incomplete pass. If the receiver is covered, a bad throw can be a 50/50 ball or worse. Our receivers can go get a ball that is well placed, but if it isn't well placed, it can cost us. Underthrows can kill you if the DB jumps the route.

We do get guys "open" occasionally, but not often enough to base the offense on it. Running precise routes can get our guys open, but it requires great timing on the play in most instances, which is not our specialty. We also don't have the speed some other teams use to get separation. OSB maybe does. Our tight ends don't. Play action only works if the defense believes you actually will run. So, the "new" pass first offense has it's own issues. (Not the least  of which is sacks, but we are back to the OL issue there.)

[Goose]

I could be mis-remembering, but I thought the play we ran against Oregon forced the safety to pick which receiver he was going to cover.  Costello's job there was to determine which receiver was in 1-on-1 coverage, not which receiver was uncovered.

In this case, it was really uncovered. It was one defender, two receivers. Pick your poison.
https://www.youtube.com/watch?v=0ILmr9p-bpc

Look at about 1:48 in. They "optioned" the Mike linebacker.

Your other examples are really examples of where the receiver tries to get separation from the DB (it can also be accomplished with a really fast receiver or with a play-action pass that catches the safeties cheating in on the run), but being able to get a bit of separation is not the same as being uncovered.

BC

Yes, uncovered is a "special case" of open. That is why I said most teams try to get a receiver "open". There are many different ways to do this, but it is a goal of most teams. The QB is instructed to "find the open man", not "find the single-covered man". We often throw to receivers that have no or almost no separation, i.e. are not "open". That  really puts the onus on KJ to throw a perfect ball ball. He often does, particularly when he has time. However, that is a lot to ask, and in any game, there will be mistakes or hurried throws. If the receiver is "open", a bad throw probably leads to an incomplete pass. If the receiver is covered, a bad throw can be a 50/50 ball or worse. Our receivers can go get a ball that is well placed, but if it isn't well placed, it can cost us. Underthrows can kill you if the DB jumps the route.

We do get guys "open" occasionally, but not often enough to base the offense on it. Running precise routes can get our guys open, but it requires great timing on the play in most instances, which is not our specialty. We also don't have the speed some other teams use to get separation. OSB maybe does. Our tight ends don't. Play action only works if the defense believes you actually will run. So, the "new" pass first offense has it's own issues. (Not the least  of which is sacks, but we are back to the OL issue there.)