Obviosuly, the Bundrage call (after review) was correct according to the rule below. However, there is no way they could go from a fumble to an incompletion based on that review. There was no conclusive visual evidence that it was an incomplete pass, there was conclusive visual evidence, however, that he was down before fumbling.
Going to the ground-Rule 2-4-3-c:
If a player goes to the ground in the act of catching a pass (with or without contact by an opponent) he must maintain complete and continuous control of the ball throughout the process of contacting the ground, whether in the field of play or in the end zone. This is also required for a player attempting to make a catch at the sideline and going to the ground out of bounds. If he loses control of the ball which then touches the ground before he regains control, it is not a catch. If he regains control inbounds prior to the ball touching the ground it is a catch.
Determining a catch-Rule 2-4-3-a:
To catch a ball means that a player:
Secures control of a live ball in flight with his hands or arms before the ball touches the ground, and
Touches the ground in bounds with any part of his body, and then
Maintains control of the ball long enough to enable him to perform an act common to the game, i.e., long enough to pitch or hand the ball, advance it, avoid or ward off an opponent, etc., and
Satisfies paragraphs b, c, and d below.