Injuries are a part of hockey and every team must battle through them at some point during the season, but all injuries are not the same. Losing some players carries much more weight than others.
During the first few games of the regular season, we are seeing the impact of injuries to indispensible players such as Nashville defenseman Ryan Ellis, Boston center Patrice Bergeron and Minnesota winger Zach Parise.
What makes a player indispensable? When players like Ellis, Bergeron and Parise are lost, their teams take a hit at both ends of the ice and the results show up on the shot counter and scoreboard. The other aspect is team construction. Superstars like Sidney Crosby and Alex Ovechkin would be tough to lose, but their teams are good enough they could survive a stretch without them. The indispensables come from teams that aren't exactly stacked top to bottom, or have already had injury troubles -- or both.
So who are the most indispensable players in the NHL? Here are 10 forwards and five defensemen whose team would be in trouble without them:
Forwards
Connor McDavid, Edmonton Oilers
Key stat: 13.2 percent relative goals for percentage in 2016-17
When the eventual Hart Trophy winner was on the ice last season, the Oilers scored 62.1 percent of the goals at even strength. When he was off, they scored only 48.9 percent. The team hasn't made major additions, meaning McDavid will again be asked to drive their success.
Ryan Getzlaf, Anaheim Ducks
Key stat: 23:02 time on ice per game, most among forwards
With Ryan Kesler, Hampus Lindholm and Sami Vatanen injured, the Ducks are leaning heavily on their 32-year-old center. Apparently Getzlaf doesn't believe in the age curve, because he continues to be a point-per-game player and dominating physical force into his 30s.
Anze Kopitar, Los Angeles Kings
Key stat: 21:17 time on ice per game, nearly two minutes more than next highest Kings forward
A fast start from Kopitar with eight points in five games has the Kings looking good at 4-0-1. They rely on him to score at even strength and power play, kill penalties and shut down opponents' No. 1 centers. Without much forward depth, the Kings will have to hope he stays hot.
Brad Marchand, Boston Bruins
Key stat: 56.0 Corsi for percentage
The B's are off to a tough start at 2-3-0, but they might not have a single win without Marchand. With star center Patrice Bergeron out, Marchand is leading the team in ice time and points and has dominated the shot counter when on ice. Boston's top scoring threat will have to carry them until Bergeron returns.
Jack Eichel, Buffalo Sabres
Key stat: Eichel's line has 10 goals this season, the rest of the team has four
The Sabres added a number of pieces in the offseason, but they've looked much the same as the last two seasons. Eichel has 64 points in 67 games dating to the start of last season, yet the Sabres as a team have been among the league's lowest scoring.
Adam Henrique, New Jersey Devils
Key stat: Fifth in the NHL in penalty kill minutes
Henrique has been a bright spot on some lowly Devils teams during the past four seasons. Now he's getting a chance to shine on a club on the rise. But while their depth may have improved, the Devils' No. 2 and No. 3 centers are both under the age of 21. They need Henrique to take the tough minutes and produce, and would be in trouble without him.
Henrik Zetterberg, Detroit Red Wings
Key stat: 20:55 average ice time per game, ninth in the NHL
Detroit may have faded as a legitimate contender, but Zetterberg keeps on trucking. Through six games, he has a higher average ice time than at any point in his career, and is flourishing, with seven points. It doesn't seem to be a small-sample fluke considering he scored 68 points last season and had a 52.2 Corsi for percentage.
Mika Zibanejad, New York Rangers
Key stat: Five goals. Next best Ranger has two.
After trading away Derek Stepan to Arizona, the Rangers are relying heavily on Zibanejad to produce. Thus far, he's come through, scoring five goals and putting 31 shots on goal through seven games. The Rangers appeared to have decent forward depth coming into the season, but Rick Nash's struggles could create a big hole up front. He has just one point and is playing only 16:15 per game.
Vincent Trocheck, Florida Panthers
Key stat: 20 shots on goal in five games
The Panthers haven't been shy about using Trocheck this season. He's playing 22:34 per game, which is even more ice time than No. 1 center Aleksander Barkov. The skilled playmaker and scorer leads the team in shots, and plays in all situations. He isn't their franchise player, but Trocheck makes the Panthers' forward group competitive.
James Neal, Vegas Golden Knights
Key stat: Six goals in six games
Few people expected the Golden Knights to be too competitive this season, but they have shown some bite behind Neal's resurgence. His production dropped last season in Nashville, but playing with the expansion franchise, the former 40-goal scorer has come out firing. Without another pure goal scorer on the roster, Vegas will need Neal to have a big year in order to keep up with the rest of the Pacific.
Defensemen
Erik Karlsson, Ottawa Senators
Key stat: 67.7 percent goals for percentage in 2017 Stanley Cup Playoffs
If there was any question about Karlsson's ability to dominate, he silenced any remaining doubters in last spring's playoff run by taking on the best competition and single-handedly carrying the Senators to the Eastern Conference Final. The Sens scored 23 goals and allowed 11 with Karlsson on the ice during the postseason. He was out of the lineup until Tuesday night, and Ottawa was -- unsurprisingly -- the NHL's worst team in Corsi for percentage to that point.
P.K. Subban, Nashville Predators
Key stat: 26:29 time on ice per game, second in the NHL
With Ryan Ellis out, there is more pressure on the Predators' top three defenders, Subban, Mattias Ekholm and Roman Josi. Subban has taken on the biggest load, picking up huge minutes and producing seven points in five games. Nashville's success starts on the blue line, so Subban will have to be at the top of his game until Ellis returns.
Brent Burns, San Jose Sharks
Key stat: 18 shots on goal in four games
After a Norris Trophy-winning season, Burns is off to a slow start with just one point in four games, but the Sharks have controlled play with him on the ice to the tune of a 59.1 Corsi for percentage. Weakened by the exit of Patrick Marleau, the Sharks can't compete without another big campaign from Burns.
Alex Pietrangelo, St. Louis Blues
Key stat: Eight points in six games
St. Louis's No. 1 defenseman is often lauded for his size and toughness, but goes underappreciated for his scoring prowess. Since becoming a full-time NHL player, he's scored between 37 and 51 points in every season and is off to a good start in 2017-18. While Pietrangelo isn't the only quality player on the Blues's blue line, there's little firepower beyond Colton Parayko and him.
Jared Spurgeon, Minnesota Wild
Key stat: Plus-7.2 percent relative Corsi
While Ryan Suter is the Wild's No. 1 D-man, Spurgeon is the possession driver. He's posted positive relative Corsi percentages for the past four seasons, and is already improving his club's shot totals when on the ice this season. His ability to race the puck up ice allows Suter to focus on locking down opposing teams' top players. There isn't another Wild defender who fits with Suter, making Spurgeon very valuable -- especially with key injuries elsewhere in the lineup to start the campaign.