Brent definitely saw Casey the whole play. If you look at the front view of that play. He led Casey. He may have thrown it a little high but he read Casey on that drift and led him on the outside right. That was a practiced play. You don't just throw that up. You had to have ran that many times. Casey was moving to his left (our right) and the ball was thrown to his upper left shoulder hence being led. That's why Coach Stock was so adamant about it on the radio.
Lee was option 1 but Casey (option 2) had great separation and ran on a straight line in the middle to his left. That's a scripted route. No doubt about it. Stock saw it and released it before he got sacked but he saw it, gave time for it to develop, and threw it to where Casey had the best shot of catching it. It was a little high but Casey was the intended target. Again, he led him.
The side view of the play looks accidental and lucky. The front view looks like it was on purpose and was a scripted play. Again, that's why Stock spoke out the way he did. Kudos to Stock.