I can see why he was red carded. Though I've never seen someone get one for that type of challenge.It was never a red card for me, very cynical tackle, but a red was very harsh.
I get it, he was trying to stop their winger from starting a counter attack but usually you pull or push the player down or block him or something like that.
I can't remember seeing some lunging at someone from behind to stop him. That seemed a bit much.
But I can also see why Arsenal fans have grievances.