Players already talked about this ad nauseum in the locker room cleanout day. They said Spags had shown that look a bunch of times and the pressure was always coming from the other side all game so they slid the protection that way. When they did, they brought it from the other side for the first time all game. Sometimes you just have to tip your hat to the other team for a great play call at a crucial time. If Cyborg doesn't totally whiff on his block, Allen likely has enough time to get the ball to Kincaid for a regular easy catch.
So in this case it was a combo of a great playcall and poor execution by the one person who could least afford to not execute on that play.