I think it's well beyond that.
The D is trash. It was trash in the playoffs with Keith, Keith did nothing when they went on their epic bender of losing last December, and sure Campbell sucks, but Skinner has more or less stepped in and given close to Smith save percentage.
The difference maker last year was Evander Kane. That's a real player. He made a real difference, you put a player on any team and have them score at a 50 goal rate and it will buoy any team significantly.
That and McDavid just took his game into outer space in the playoffs.
But it's still a poorly built team overall and that becomes very evident once you remove Kane. They sucked last year too without him and this year ... they look basically exactly the same without him.
His ability to score some goals lifts the team tremendously and gives McDavid/Drai life because losers like Puljujarvi, Yamamoto, etc. are better off just staying at home and sleeping in, you can't trust those guys when you're going to war.