When the Toronto Maple Leafs added John Tavares on the first day of NHL free agency, they added one of the NHL's top-ten centers. Their offensive arsenal became arguably the NHL's most dangerous, and their top-four core potentially the most expensive in a year's time. In short, by signing Tavares, the Maple Leafs created a good problem to have.

What GM Kyle Dubas does next is uncertain, but publicly, he's said his intention is to keep his core together and that he thinks he can. Time will tell if that's possible, but adding Tavares makes predicting the Leafs' lineup this upcoming season both exciting and interesting.

What will their forward lines look like? What else is coming? What can Dubas do with his blue line? Is the team good enough the way it is?

Offensive Pairings

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In today's NHL, the common trend is to pair forwards together. The Edmonton Oilers did so in 2016-17 with Connor McDavid and Leon Draisaitl, the Penguins have done so with Evgeni Malkin and Sidney Crosby and the Washington Capitals just won the Stanley Cup with Alex Ovechkin and Evgeni Kuznetsov. Toronto is following that lead and taking it to a whole new level.

Adding Tavares gives the Leafs and two lines with two pairings that are extremely dangerous to the opposition. When Auston Matthews and Willam Nylander aren't swarming defenses with their dynamic skillset, Tavares and Mitch Marner can come out of the ice and make the defense pay. When you consider the Leafs have Patrick Marleau, Nazim Kadri, and Zach Hyman who they can add to those combinations, the optics of what the Leafs can throw out there on any given shift is scary.

RELATED: WINNERS AND LOSERS IN FIRST DAY OF NHL FREE AGENCY

Center Depth

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With the addition of Tavares, the Leafs have the best one-to-three center depth chart in the NHL. Between Matthews and Tavares, you can flip a coin to decide who is your first-line center with the other playing second fiddle. In reality, it's more like Option 1 and Option 1A. Then add Kadri to the equation— a player who had 32 goals and 55 points last season— and on some NHL teams, you have Option 1C.

The challenge for the Leafs will be getting these players enough minutes and not sacrificing the role someone like Kadri plays. Will they move him to wing sometimes to keep his minutes up? Will they be challenged to keep him active and happy?

Questionable Blue Line

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The one area the Leafs have not addressed this summer is their weak blue line. That said, there is still an opportunity to do so.

Tavares is great and makes the Leafs offense even better than it already was. But, is a top-pair of Morgan Rielly and Jake Gardiner enough? Probably not. Thus, if the Leafs are planning to roll out the season with those two as their top pair on defense and have Nikita Zaitsev and Ron Hainsey to back them up, Toronto will need to use some of the cap space they still have this season to add some much-needed help.

There were rumors the Leafs were in on free agent Calvin de Haan, and while he signed in Carolina, the Leafs should continue to pursue an upgrade. Toby Enstrom and Brooks Orpik are still available via free agency and Justin Faulk or Torey Krug might be available in trade. All are shorter-term options that still give Toronto flexibility to make future deals.

RELATED: HOW JOHN TAVARES SIGNING IN TORONTO ROCKED THE NHL

The 2018-19 Depth Chart

As it sits right now, the only weakness the Leafs have is on their blueline and potentially a left winger on their third line. If they can fill in those spots with value contracts on free agency (and there are a ton of those players still available), the Leafs are a team to watch out for this season.

They'll be an immediate contender in the Eastern Conference, challenging teams like Washington and Tampa Bay and they should be good a contender for the Presidents' Trophy.

RELATED: HOW KYLE DUBAS WILL KEEP THE LEAFS STAR PLAYERS AFTER SIGNING TAVARES