Todd McLellan's release from the Edmonton Oilers on Tuesday made for the fourth coaching casualty in the NHL this season. If you we consider in 2017-18, no coaches were fired during the season at all, it's hard to fathom how, to date, McLellan, John Stevens (LA), Joel Quenneville (Chicago) and Mike Yeo (St. Louis) have all been let go and most before the respective teams hit the 20-game mark of the 2018-19 regular season.

So why the change? What makes this season so much different than last season and why are teams so quick to make a change? If we look at reasons teams make coaching changes in general, what happened in each team's particular case and the general changes year to year in the NHL, we can see both similarities and differences between this year and last and why these four may not be the final names on the casualty list.

Disappointing Seasons

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In some cases, the firings that happened this year are a direct result of unexpected and disappointing seasons. Perhaps in Edmonton and Chicago, things weren't dire, but in St. Louis and Los Angeles they were, with the Oilers and Blackhawks not far behind.

If we take the Blues as an example, here's a team who went out this past offseason and loaded up on offensive talent. They brought back David Perron, added Tyler Bozak, traded for Ryan O'Reilly and signed Patrick Maroon. They still had stars like Vladimir Tarasenko and should have been a deep team contending for a playoff spot, predicted to go deep in the postseason. Instead, they sit second-last in the NHL standings with the fifth-worst goals-for total in the league. Whatever that team envisioned clearly hadn't been panning out. The only team worse? The Los Angeles Kings.

Related: Biggest NHL Rumors This Week - November 18, 2018

Parity in the NHL

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Moreso than ever before, there's great parity in the NHL — meaning, any team can beat any team at any given time. Sure, there are stacked teams that were clear favorites from the first puck drop of the 2018-19 campaign, but those teams represent only a select few of the 31 NHL franchises that make up the league. Only six total points separate the third-place team from the fifteenth-placed team in the NHL standings, meaning a three-game losing streak or three-game winning streak puts any team right back in the conversation.

When McLellan was let go in Edmonton, general manager Peter Chiarelli said of the decision, one or two points can be the difference between making or missing the playoffs. He's right. In the NHL, an overtime win or loss in the regular season could mean being in or out of the postseason. Every game, every period and every point counts. If general managers get a sense that the team isn't taking advantage of earning those points, they look to how to correct the problem. Sometimes it's players, but more often than not, the coach becomes the scapegoat. Sometimes, a quick change wakes a team up and kicks an organization back into full-effort mode.

Related: Oilers Fire Todd McLellan And Hire Ken Hitchcock

Scapegoats

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Unfortunately, for some of these coaches, the wrong person was actually fired. In Chicago, fans and media were floored that Quenneville was let go when you consider the mess the Blackhawks GM had made of the team. Bad contracts, worse trades, and awful cap management left the coach to lead a team that was not nearly competitive enough. Quenneville wasn't playing with a full deck. It was a similar situation in Edmonton where Peter Chiarelli has to be on the hot seat now, after trading Taylor Hall, Jordan Eberle, and others, yet hasn't improved the team's defense. He's wasting the best years of Connor McDavid's career. In LA, Stevens was working with an aging team that likely isn't as good as some suggested they might be.

It's easy as a GM to grasp play that one final card before you're out on your a$$ and fire the coach. If you're lucky, things turn around and you salvage your job. If not, you prolonged the inevitable.

What This Means

No matter why these coaches were fired, don't expect these four to be the only ones served their walking papers. The New Jersey Devils, Pittsburgh Penguins, Florida Panthers and Philadelphia Flyers are having less-than-stellar seasons compared to expectations.

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