That bobbling animation is pretty typical of any kind of catch, be bit a reception or an interception. I remember reading some threads about that bobbling that Bort chimed in on a long time ago. As I recall he pretty much confirmed that when you see the ball do that it represents a player either juggling the ball (i.e. deflecting it straight up and then catching it on his 2nd try when it stays within his 'catch radius') or otherwise taking a moment to secure the ball.
Strangely enough when I see a DB or LB put a good hit on a player while the ball is doing that it usually results in an incomplete pass and credits the defender with a deflection. I guess that is supposed to represent a defender reaching in an knocking the ball loose before the receiver gets possession. Just as an example here's one from the last time your former team, Paper Street, played my team, the Bandits.
Looks like the receivers gets a hand on the ball and then the LB breaks up the catch.
http://goallineblitz.com/game/replay.pl?game_id=151384&pbp_id=1502772Sometimes the ball isn't even moving and a hit still knocks it loose while calling it a deflection. This almost looks like a catch and then a step before the CB comes in.
http://goallineblitz.com/game/replay.pl?game_id=151384&pbp_id=1499235
