That control does have to remain throughout the process of the catch. Tate had at a minimum marginal control all the way until the whistle blew.
Wrong. Here is the rule. See anything in there about marginal control first of all? But in order for it to be simultaneous possession both have to maintain joint possesion all the way through. At the very end Jennings is the one that had possession on the ground. Tate did not maintain possession throughout. You can see Jennings catch the ball and Tate's hand come in afterwards. So Tate came in afterwards and then Jennings had it on the ground. Tate failed on both points to maintain possession throughout.
Rules governing this:
Applicable rules to the play are as follows:
A player (or players) jumping in the air has not legally gained possession of the ball until he satisfies the elements of a catch listed here.
Rule 8, Section 1, Article 3 of the NFL Rule Book defines a catch:
A forward pass is complete (by the offense) or intercepted (by the defense) if a player, who is inbounds:
(a) secures control of the ball in his hands or arms prior to the ball touching the ground; and
(b) touches the ground inbounds with both feet or with any part of his body other than his hands; and
(c) maintains control of the ball long enough, after (a) and (b) have been fulfilled, to enable him to perform any act common to the game (i.e., maintaining control long enough to pitch it, pass it, advance with it, or avoid or ward off an opponent, etc.).
When a player (or players) is going to the ground in the attempt to catch a pass, Rule 8, Section 1, Article 3, Item 1 states:
Player Going to the Ground. If a player goes to the ground in the act of catching a pass (with or without contact by an opponent), he must maintain control of the ball throughout the process of contacting the ground, whether in the field of play or the end zone. If he loses control of the ball, and the ball touches the ground before he regains control, the pass is incomplete. If he regains control prior to the ball touching the ground, the pass is complete.
Rule 8, Section 1, Article 3, Item 5 states:
Simultaneous Catch. If a pass is caught simultaneously by two eligible opponents, and both players retain it, the ball belongs to the passers. It is not a simultaneous catch if a player gains control first and an opponent subsequently gains joint control. If the ball is muffed after simultaneous touching by two such players, all the players of the passing team become eligible to catch the loose ball.