Quoting: Leafsfan98
And the Leafs are wrong for not blowing it up
Easier said then done since all 5 of their core players hold full trade protection now, but even if they can trade someone it needs to make sense. Let's just assume trade protection isn't an issue and look at the trading each guy.
Matthews - He'll get the biggest return, but trading him also has the biggest potential for being a lost trade. In terms of roster construction, he's the most important player out of the 5 as their 1C, so even if they can fill a ton of other holes, they'll have a giant one down the middle. Simple put he's not going anywhere.
Tavares - If they Leafs retain like 3M, they could probably get out from his contract, and get some decent value. They would need a 2C replacement which they could perhaps get in Chandler Stephenson and save like 2M on the season. They could also hope Domi could hold down the 2C role and worry about it down the road if it becomes an issue. If they are unable to trade him, he might just be phased out of the core and dropped from the team entirely even if he's an effective player still. They could focus on the 2C spot over top 4 D in the off-season but that's probably going to be viewed as more of the same. Moving Tavares alone should give them enough flexibility to make significant changes and moving their captain (or making him an alternate) might be the shakeup that the locker room needs.
Nylander - The Leafs have two first-line right-wingers, making it an area of strength, so they could look to restructure their core by moving one of them. Nylander being their most consistent playoff performer, so if they do trade him it better be for a young top 2 D (like Power or Seider) or a similar aged RHD (like Ekblad) or perhaps a young 2C (that is proven) , chances of any of those happening are slim to none so he should be considered safe. If he was moved, he also should not be the only one.
Marner- He has been the opposite of Nylander in the playoffs, and he's likely to command 0.5-1M more than Nylander on an extension. He is the more complete player of the two and higher producer but I do think he's less of an offensive threat even if he produces more. Trading him and getting good value out of him would likely be challenging but it's probably the most logical move if there is a good deal to be made, and could be a stand-alone move. Marner is not a player that you just trade for pennies on the dollar for cap space to spend in free agency.
Rielly - The Leafs' defense is the area that needs the most work, so moving Rielly would likely be a non-starter unless the Leafs. He's on a team friendly-deal, so trading him would only make sense with the move of another core player as well, and only if they are ending up with a top 2 D and two additional top 4 D in the end (i.e., not counting McCabe).