Let's say a receiver jumps in the air, catches the ball and is immediately hit by a defender, lands on his back and the ball pops out. Is that a catch or not?
That happens in just about every game I ever watch. It's not a catch because he never "had contol".
No, it is not a catch because he didn't make a football move. The receiver had control - the back is the same thing as two feet.
See what I mean, it's not as simple as it seems.