Re: The improbable improvement of Kareem Jackson
On the almost-TD pass to Jean, the Dolphins DB was pretty much in phase with the receiver, but he never turned his head to locate the ball. He wasn't quite close enough to the side line.
Turning his head wouldn't have helped him anyway.
By concentrating on the receiver's eyes and then the hand/arm;
he was able to put a hand on Jean's right shoulder and arm (just a hair before the ball arrived).
Jean couldn't gathered both hands together sooner to secure the catch.
Turning his head here would only hurt the CB more; he wouldn't be able to pin-point the arrival location of the ball.
Also, if it was a back-shoulder fade, the CB would have been in no position to defend the play.