I don't think it's so much "after a win" as it is a lack of data. They've played one game, against a bad team, at the beginning of the season, under weird international circumstances. We really haven't seen what's going on with this roster yet.
As I stated, way more important than the bottom 6 assortment is the top 6 and the whole defense learning to do what the coaches want them to. It's a whole new even strength system, AND a whole new PP, AND a whole new PK. It's a ton to learn. Those transitions are hard, and there's a lot to take on, and it's difficult to get a dozen grown men to learn new habits all at once after playing for half a decade under a bored babysitter.
Like it or not, the young plugs who had a good preseason got the roster spots, for now. They had good preseasons because they did what was asked of them, nothing more, nothing less. They didn't shine because they're more talented than the high-end prospects who aren't on the roster, they were effective and viewed favorably by the coaches because they played AV's game right off the bat and kinda stuck with it. In the very least, they're not a headache, even if they're nothing at all special.
None of us have any way of knowing what the thought process behind the final roster decisions, but if I have to posit, I think it'd be the notion that the staff has bigger fish to fry. I'd want Provorov and Voracek and Hayes and Hart and Sanheim and Ghost and Giroux, et. al, to all be on the same page, especially so those guys can be the example for the Frosts and Farabees of the world. Vigneault made it pretty clear that he didn't think the veteran group were fully there on the timeline he expected. When they're all up to speed and killing it, perhaps we'll see a bit more roster experimentation...but for better or worse, I don't see it coming this week or next.