They've been the better team in 2/5 games by my eye. They boast bottom-10 shot-share metrics at 5-on-5, although they grade out better by xG. They are shooting 13% at evens, which will have to fall back, no matter how elite their top end, and they've received below-average goaltending. The SH% will fall back a bit, but the 5-on-5 stuff can be roughly sustainable provided the goaltending can remain at league average. Just tread water without McDavid on, and then clobber while he's off. Obviously they want to be better than that but that's not the roster they currently have. If McDavid's line can keep scoring 60% of the goals when he's out there (he's done it for a full season before) then they'll be in the playoff mix if no one else falls off.
Where the Oilers have made completely unsustainable headway is on special teams. No one has been better, with the 2nd best PP and PK at 41% and 94% respectively. There is a possibility they remain a top special teams outfit and linger in the top-5 for both but won't be at those extremes. They are probably out of yesterday's game if the Rangers don't clang iron a couple of times in the 1st period on their PP. If the Oilers can hang in the top-5/10 on both special teams that's another road map to playoff contention.
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Anyways, despite the wins, I don't really see a whole lot of difference between the from the pre-season expectations. This still probably isn't a playoff team, but the path there is the same as you would have charted before the year: McDavid and Draisaitl crush at 5-on-5, the depth pieces play to roughly break-even, the new adds plus coaching help gain a special-teams advantage, the goaltending is good enough to give the team a chance.
I still don't trust this goaltending tandem. I like Smith but I don't trust his health to hold up. McDavid's still giving up too much of the shot-share at 5-on-5 for me to trust the early returns. Anything can happen with special teams in a small sample so we'll see if this is something they can sustain.