I don't think there was and it was one of those plays where it looked worse than it was. Also it was a play where the defender had already determined where he was going to make the hit and Knox had to reach backwards for the ball. Hard to say there was real intent there. I'm surprised it generated a fine.
I understand the need to protect players and I am not one of those guys that thinks the golden era of football was when you could decapitate someone. However I really think they need to review these plays more closely. It's pretty common where the offensive player changes the strike zone at the last second. Yes it ends up a bad hit but it's not the defender's fault. It's fairly easy to see by replay if the defender's angle of attack would have been fine except for the WR or RB has now changed position.