The word "controversial" appears in some reports on ESPN - they must be joking. A foot higher than the waist, showing studs, aiming for a player is dangerous play. Going towards the head is even more dangerous. It wasn't intentional but still a red.
If they want to discuss controversial red cards what about Kyle Walker and Raheem Sterling.
I must add that Craig Burley on ESPN was vehemently adamant it was a definite RED.
Its only "controversial" because so many cannot seem to get their head around the fact that a challenge doesnt have to be intentionally dangerous to be a red card offense