He did not win game 2 by himself. Stop overrating him please or watch what some of these players that actually perform in the playoffs are doing.
He left in game 4 before period 3. That was essentially a must-win game and they laid an egg. Worst performance at home since game 7 against Montreal or David Ayres and the game was over. Was he injured? We don't know anything because they aren't telling us anything. Nobody can show us when this injury happened. First it was illness, then it was a knee injury, and now it's a head injury. But don't ask Matthews, he won't tell you why he couldn't play... in the playoffs.
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But he wasn't alone. The Leafs #2 guy did the same thing. But they walk on water so don't dare mention it.
He pulled chute when the series was lost and then somehow came back when the series was tied.
There's a reason why the Stanley Cup is what it is. Even in the softest era of hockey ever. Barkov got hit in the head and missed no time and had a game better than any Leafs core member has ever played.