If you watch Slavin at all you'd know he is the best shut down D in the league. He's the McDavid of defensive players.
I agree with others that McDonagh should be an option ahead of Hedman (who has never been that great defensively), and that Karlsson shouldn't be an option, at least not until he proves his newfound defense ability for longer.
And gets buried with goals against. Until this year he was dead last in goals against. There's 62 D-men in the league playing against top lines, most of them far better defensively. I don't get it, I've watched a half dozen Leafs games this year and Rielly turns the puck over a lot, misses assignments sometimes and takes weird angles. He's perhaps improved to the point of being unremarkable defensively but it's really weird that anybody, even Leafs fans, would suggest he's the best defender. Some nights he's obviously the worst on his own team!