Joined: May 2016
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As to your other point. Yes, they have a less scoring chances against relative to their offensive chances for, but that doesn't hold up for raw chances against.
This past season (their defensively improved season), they were in the middle third when it came to high and medium danger shots against. They were top 2 in that same metric in that same category on offense.
So when comparing relative numbers (Shots For %, Scoring Chances For %, Corsi & Fenwick For %), Toronto is going to be near the top because they generate so much offensively, but their raw defensive output is not near the top of the league.