Like you said, Crabtree may not have been open at the time.But, at the same time, I think maybe he DID want to throw it. If Brown wasn’t one of his first reads, why didn’t he throw to the wide open Crabtree in the middle of the field? Only reason for that would be Crabtree wasn’t open until after Joe looked at him, which is possible but I’m not so sure. I think they knew Brown would be wide open.
Reads, theoretically, should be boom, boom, boom. Really quick.
Like I said, that's generally a very dangerous throw and one I'd only make if it's wide open, like John Brown was.