If the NFL is serious about player safety, it has to call it both ways.  Pollard had become the receiver, made a play on the ball (missed it), and Celek hit him in the helmet with his helmet.  Pollard (I hate to say it, because the guy plays a cheap game.) was a defenseless receiver.  It should have been a penalty.  Of course, the commentators said nothing, but I guarantee that if it had been Celek getting hit, with no flag, they would have noticed.