If you're the BJ, you gotta think that something very screwy went wrong here. How could a player get behind you without you noticing? It's not like the kid had time to run way downfield on the other side of the field, then dance across so far behind you that your peripheral doesn't catch him.
I think that BJ should have had a red flag go up in his head. But I can see how if you're not 100% confident in your game, that your head is scratching on this one and you just think that you gotta eat the non-call.
However, I wouldn't expect the official to be fired over it.
Jim makes a good point to make sure the guy leaving the field doesn't come back in.
And why did the players knowingly get in on this play? Would they follow the coach if he jumped off a bridge?