This was a tough one.
He clearly caught the ball and then he took 2 steps then he fumbled the ball going down out of bounds.
Apparently the NFL felt that those 2 steps were legitimate to call it a catch. Additionally he may have taken a 3rd step out of bound before fumbling it. And even though one of the steps is out of bounds it still demonstrates control of the football before going to the ground.
Not sure if that play was reviewed multiple times that we would get the same answer.
