We're not even a month into the season, so each team's performance is still defined by a small sample size. For this week's ESPN NHL Power Rankings -- voted on as always by ESPN's panel of experts -- we identify one unsustainable stat for all 31 teams.
Note: These rankings reflect which teams our voters think would win head-to-head matchups. Higher-ranked teams would be favored against lower-ranked teams.
Previous ranking: 2
The reigning Presidents' Trophy winners look sharp in most areas of their game. But the power play, which hit at a 21.2 percent clip in 2017-18, isn't clicking. The Predators have scored only three extra-man goals on 31 opportunities (9.7 percent).
Previous ranking: 3
The Lightning, a Stanley Cup favorite, look great defensively. We'd hate to jinx it, but can they continue to be this good on the penalty kill? (They've killed off 97.0 percent of penalties so far this season).
Previous ranking: 11
Previous ranking: 1
Even though he has cooled down recently, Matthews is at a goal-per-game pace. As he jostles with David Pastrnak for the league lead in goals, the question is how long can the young American stay on top?
Previous ranking: 8
Josh Morrissey's average ice time is up three minutes from last season, while he has earned a promotion to the top power play. Here's the ridiculous stat for Morrissey he might not maintain: 10.1 points per 60 minutes at 5-on-4.
Previous ranking: 4
David Pastrnak, Patrice Bergeron and Brad Marchand have combined for 44 points this season, the most of any NHL trio. One of those three has been involved in 23 of the Bruins' 31 goals this season. A dominant top line is a good problem to have, but the teams playing deepest into the spring usually have more balance.
Previous ranking: 20
The Sharks are a great possession team, peppering opponents with shots and pressure. However, goaltender Martin Jones isn't playing to his full potential lately. He's sporting just a .891 save percentage at even strength. We've seen better from Jones, and he should get back on track.
Previous ranking: 7
The Canes are Corsi gods, but that's nothing new. Still, we should marvel at the fact that Carolina boasts three lines with a Corsi for percentage over 57.
Previous ranking: 9
Previous ranking: 5
It's not that we're skeptical that Kyle Palmieri can't sustain his hot start, we just want to point out that with his seven goals through the team's first six games, he has a 31.8 shooting percentage.
11. Anaheim Ducks
Previous ranking: 6
John Gibson is sporting a 1.93 goals-against average, so say hello to your early Vezina Trophy front-runner. But the Ducks have let Gibson stand on his head by giving up a league-high 294 shots through eight games. That defensive irresponsibility tends to get exposed, eventually.
Previous ranking: 13
The Pens had the league's best power play last season but haven't been given the chance to fully capitalize. Pittsburgh has had only 18 power-play opportunities through seven games, which is fewest in the league.
13. Calgary Flames
Previous ranking: 14
The Flames have been bailed out a bit lately by good backup goaltending. David Rittich saved 81 of 85 shots on a two-game trip. Can he keep up with his .950 save percentage and 1.83 GAA to relieve Mike Smith this season?
Previous ranking: 10
The demise of the Blackhawks might have been exaggerated, and an offensive surge is partially to thank. Chicago leads the league with 28 even-strength goals after finishing last season 20th in that category. Maybe there is some gas left in the tank, after all.
Previous ranking: 12
Things need to shore up defensively for a team giving up a league-high 3.51 goals per 60 minutes at even strength. Then again, the Blue Jackets weathered the first three weeks without their No. 1 defenseman, Seth Jones.
Previous ranking: 19
The Habs have had a terrific start, even without Shea Weber. In fact, Weber's partner, Mike Reilly, has formed a great tandem with Noah Juulsen. They have a plus-8 goal differential in 121 minutes together. Maybe this team isn't as bad as many pundits suggested.
17. Minnesota Wild
Previous ranking: 18
Coach Bruce Boudreau recently told his players he wants them to take more shots, but they also have to limit the number of shots they're allowing: 36.8 per game, the second-highest mark in the league.
Previous ranking: 21
The Golden Misfits are trying to recapture the magic of their first season, as they weather injuries (Paul Stastny) and suspensions (Nate Schmidt). A league-low 7.1 percent (2-for-28) power play is one of the biggest areas for improvement.
Previous ranking: 16
The Canucks have played 10 games this season, and seven were on the road. The fact that they've won four of those games is key to their better-than-expected start. Can this continue?
Previous ranking: 20
The goaltending situation is not ideal, but these two numbers stick out like a sore thumb. The Flyers have given up 12 goals in the first period, a league high. The Flyers have given up 15 goals in the third period, also a league high.
21. Buffalo Sabres
Previous ranking: 23
The biggest number for the Sabres right now is five: their win total so far. It's only the second time the team has won more than three games in October over the past seven seasons. Arrow's pointing up!
22. Dallas Stars
Previous ranking: 17
As partner to John Klingberg, the 24-year-old Esa Lindell has taken on a big role in Dallas. He's third in the league with 21:03 minutes of even-strength ice time per game (trailing only Kris Letang and Ryan Suter).
23. St. Louis Blues
Previous ranking: 22
There is plenty that ails St. Louis these days. So perhaps this stat isn't as damning as it is telling: When the top pairing of Alex Pietrangelo and Jay Bouwmeester are on the ice, they have a goal differential of minus-7. Not great, but there's room for improvement.
24. Ottawa Senators
Previous ranking: 24
The Senators may be winning more games than expected, but once again they're not a great team in terms of possession, as their 43.69 Corsi for percentage ranks 28th in the league. They've allowed exactly as many goals as they've allowed, which somehow feels like overachieving.
25. Edmonton Oilers
Previous ranking: 27
The Oilers are too reliant on their star. Connor McDavid has scored or assisted on 72 percent of Edmonton's 18 goals, leading all NHL forwards with 19:43 even-strength ice time per game. (Patrick Kane is next closest at 17:51.) He needs some help.
Previous ranking: 25
Valtteri Filppula has emerged as an offensive early hero, with four goals in his first eight games. He hasn't scored more than 12 goals since 2014-15. Can he possibly keep this up?
27. Florida Panthers
Previous ranking: 30
The Panthers haven't looked sharp, and their performance in the second period has been worrisome. They have a minus-10 goal differential (eight goals for, 18 against) in the second frame. That will need to tighten up for them to get back in the playoffs this season.
Previous ranking: 26
There are some serious offensive woes in Los Angeles, but few areas are as troublesome as the power play; the Kings couldn't connect with the extra man for the first two weeks of the season. They're still 0-for-15 in five road games. That must (and should) improve.
29. New York Rangers
Previous ranking: 28
The young Blueshirts are firing 33 shots per game, which is generally a good thing. Their shooting percentage, however, is one of the league's worst, at 5.33 percent, which explains why they are a bottom-seven team in scoring.
30. Arizona Coyotes
Previous ranking: 29
A trendy sleeper team is sleeping on offense, scoring only 1.39 goals per 60 minutes at even strength (and 1.75 goals per game in general, also a league low). Reinforcements might help: Alex Galchenyuk's season debut is imminent.
Previous ranking: 31
Oh, where to begin with the Red Wings? They have a league-worst minus-19 goal differential, as they are giving up a league-worst 4.22 goals per game. It'll get better. Or they'll have a great shot at landing Jack Hughes next summer.