The Toronto Maple Leafs have made extensive changes to their roster, but it might not be enough.

Whether it's remaking the bottom-six group of forwards almost entirely, adding high-end talent in the net in the form of winger Kirill Marchenko, adding a goaltender with pedigree in Sergei Bobrovsky, things look drastically different than last season.

But their defense corps — the area they needed the most help in — remains largely the same aside from the addition of Darren Raddysh. Through the team's first 17 games of the season, it's evident that is still the area that's holding them back from taking the next competitive step as a franchise.

So what will GM John Chayka do to improve his blue line? Here are some educated guesses of potential targets he could trade for:

The 32-year-old Ristolainen is a pure rental asset, and with a $5.1 million salary, he's an affordable option. There are downsides to Ristolainen's game and the underlying analytics don't favor him, but he's a right-shot D-man with a big body at 6-foot-4 who has some snarl to his game.

The Flyers won't ask for the sun and stars in any Ristolainen trade, but he's almost certainly going to be moved by Philadelphia GM Daniel Briere, and Toronto could put in a winning trade package for him.

Samberg is a cost-controlled defenseman under contract through the 2027-28 season, and he's been capable of playing top-four minutes at the relative bargain salary of $5.7 million per year.

The 27-year-old also has a big physical frame at 6-foot-4, and he only has a modified no-trade clause allowing him to veto a deal to one of six teams of his choice.

The Jets' extended slump may push Winnipeg GM Kevin Cheveldayoff to sell off some parts, and Samberg would get him a solid return – from the Leafs, or some other team with Stanley Cup playoff aspirations. 

Nikishin's contract saga dragged into the regular-season before he agreed to a one-year, $3 million contract. He will be an RFA next summer, doesn't have any trade protection, and he's already shown that he's willing to sit out until his financial demands are met.

Chayka would need assurance that Nikishin is amenable to signing a long-term deal with Toronto. But he has the upside the Leafs are looking for, and at 25 years old, his best years are still ahead of him.

The Maple Leafs brought Swedish legends Mats Sundin and Daniel Alfredsson into the organization this summer, so Karlsson could feel right at home in Toronto.

Karlsson's individual numbers with the Penguins — 13 assists and 16 points in 15 games — are great. The 36-year-old is a right-shot defenseman, a UFA at season's end, and his full no-move clause means he controls his destiny.

Toronto needs more of a shutdown D-man, but there are few low-cost options available that fit that mold. Karlsson is the type of player that doesn't come around very often, and would be a home-run acquisition for Chayka, but he'll have to pay a heavy price to get him.

Josi is a Predators icon, but he's under contract for one more season at $9 million, and at 36, his peak years are behind him. He'd instantly be one of Toronto's top blueliners, but he has a full no-move clause, and after so many years in the calm of Tennessee, going to Toronto might not be a move he'd want to make.

But Chayka is quickly becoming famous for taking big swings, and landing Josi would be a master stroke on his part. 

Honorable mentions: Nick Perbix, Nashville Predators; Zach Whitecloud, Calgary Flames

See more of The Hockey News on Google and save us as a preferred source. Get the latest news and trending stories by subscribing to our newsletter here. And share your thoughts by commenting below the article on THN.com or creating your own post in our community forum.