Few expected the Toronto Maple Leafs to be this good, this soon.

Yes, hope abounded after a 30th-place finish in 2015-16 resulted in a draft-lottery win and the selection of Auston Matthews, who joined a prospect pool that already included Mitch Marner and William Nylander.

But all three needed to hit the ground running as rookies, and a host of other pieces had to fall into place for Toronto to contend for a 2016-17 playoff spot - much less clinch one.

That's exactly what happened. Then the upstart Leafs gave the Washington Capitals all they could handle in an opening-round loss, signaling the dawn of a new era in the center of the hockey universe.

So have the Leafs finally arrived? Can they be penned in as a playoff team and penciled in as legitimate Stanley Cup contenders beginning this season?

Not so fast.

The numbers

On the positive side, the Leafs ranked fifth in goals (3.05) and fourth in shots (31.9) on a per-game basis last season. On the other hand, they allowed a 22nd-ranked 2.85 goals against per game, and only the Sabres and Coyotes allowed more average shots against.

Zooming out a bit, Toronto's Corsi For rating at even strength was a 13th-ranked 50.38, meaning shot attempts for and against them were fairly even.

Further to that, the Leafs ranked 12th in PDO in five-on-five play, as a somewhat inflated shooting percentage (8.3) coupled with their save percentage (92.92) added up to 100.59. As a reminder, any team with a PDO over 100 is perceived as having a measure of good luck on its side, and regression closer to that number is expected sooner or later.

In all situations, Toronto's PDO came in a bit higher at 100.83 (9.55 shooting percentage + 91.27 save percentage), good for 10th overall. The Leafs' offense was boosted by a second-ranked power-play success rate of 23.8 percent, and the club was able to kill 82.5 percent of its penalties, again good for 10th in the league.

These base numbers suggest the Leafs played slightly over their heads last season, but not so much that a major decline would seem imminent.

An apple a day ...

It's in the medical department that luck really appears to have been on the Leafs' side. Toronto's top 10 scoring forwards (minus Josh Leivo, who played only 13 games) missed a total of 10 games between them due to injury.

The defense remained relatively healthy, too. Jake Gardiner and Nikita Zaitsev played in all 82 games, while Matt Hunwick (10), Roman Polak (seven), and, most notably, Morgan Rielly (five) missed 22 games combined. The big loser on this front was Martin Marincin, who missed 17 games in the first half of the season and was never able to re-establish himself in the lineup.

In net, Frederik Andersen suffered a pair of upper-body injuries, the second occurring in the penultimate game of the season wherein Toronto clinched its playoff spot. Overall, Andersen made 66 starts, second-most among all goalies.

The big addition to this group this summer was Patrick Marleau, who hasn't missed a regular-season game since 2008-09. He will, however, turn 38 prior to opening night.

Altogether, the Leafs' remarkable good health played a role in their success last season, and there's no certainty that luck will continue.

A crowded field

Finally, consider the competition.

Expected to lead the way in the Atlantic last season, the Florida teams were beset by significant injuries early on. The Lightning and Panthers are expected to rebound in 2017-18, and things won't get any easier elsewhere in a competitive Eastern Conference for a Leafs team no longer able to take opponents by surprise.

Yes, the future is bright, and something special - perhaps even great - appears to be brewing. But nothing is guaranteed in today's NHL, and expecting a clear upward trajectory with zero obstacles would be foolish.

Are the Leafs in for a major regression? Probably not, but several teams will be vying for their playoff spot, and the competition will look to keep Toronto's young guns in check all season long, should - and this is key - they remain healthy.

It's a promising group, but the Leafs' immediate return to the postseason isn't set in stone.

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