No, he wasn't.
If he made a mistake and then we lost the game by a goal, its not scapegoating to say he cost us the game.
Yes, he was. Dave was almost universally criticized for costing us the FA Cup, a criticism which I don’t agree with but I’m obviously wrong about that. And he was universally criticized for his mistakes (the ball to Maguire, which was Maguire’s fault…and Dave’s mistake later, which he alone is accountable for), the second leg v Sevilla, a criticism I agree with although I don’t go as far as Dave’s critics hear that Dave alone cost us the EL title.
But the truth is that we were played off the park by City, which no one argues did not deserve their FA Cup victory over us on the day. And in truth Sevilla beat us comprehensively in the second leg and in no way was all Dave’s fault; and in the first leg we lost control of midfield late and conceded two freak own goals which Dave could do nothing about, but for which he was mercilessly hammered here anyway because it was oh so easy to make Dave our whipping boy by then.
No one argues that Dave alone cost us the PL trophy, so we’re good there. But the caf and the larger social media hysteria machine is in near-universal agreement that Dave cost us both the FA Cup and the EL trophy. Feel free to deny this, but such denial would be laughable.