The only pairing I’m sure of next season is Muzzin-Holl. They’ve become our shutdown and matchup pairing. The rest is mostly up in the air.
Rielly will of course be anchoring the left side on the next pair, but his partner is still a mystery, and I think it’s between Dermott and Lehtonen. Dermott has always been the player mentioned when people try to think of someone moving from left d to the right side, but there is a case for Lehtonen to be there.
Lehtonen is left handed but said he’s comfortable playing the right side. He’ll be new to North American ice but he won’t be a stranger to NHL competition, as he was a heavily relied upon in the last IIHF Championship when Finland won gold. He’s said to be a signing who can step right in and play in the NHL with little transition needed. Rielly I find tends to play better with a partner who doesn’t need too much hand holding, and the level of competition he’ll face Lehtonen should be capable of handling.
Dermott whenever he’s played the right side has not been all that good imo. When he’s on the left side he looks a lot more comfortable and plays more effectively. However he has a big advantage over Lehtonen, that being the fact that he’s played in the NHL going on four years now, and he’s been in the Leafs organization since 2015. He knows the guys in the room and has played with most of the other defensemen. He’s also been relied upon in big minutes, especially this season given our injury troubles.
Whoever loses that battle will be placed on the third pair, and then it's a battle between Liljegren and Sandin. If Dermott and Lehtonen can switch to and effectively play the right side then it shouldn't matter who wins out between Sandin and Liljegren. If Dermott does become Rielly's partner then the platoon system with Lehtonen, Sandin, and Liljegren can take place. If it's Lehtonen with Rielly and Dermott on the third pair then it'll just be Sandin and Liljegren having to switch out since I doubt Dermott would be willing to (nor should he) sit out every now and again.