I think it's worth considering how much can we reasonably expect a center to elevate his wingers, particularly when you're trying to elevate them beyond their 'natural' level. We talk about this a lot with Krejci because of his situation, but is Bergeron any better? Probably not so long ago Bergy could make magic with just about anybody, but the evidence says not anymore. When Pasta was out at the start of this season, the top line generated very little 5v5 offense, even with Marchand on it. Even now, with Pasta struggling, it's again not doing a whole lot.
Simple fact is we have two centres who are in their mid-30s where it becomes increasingly harder to drive performance by your own dynamism and sheer willingness to make things happen. Without genuine quality on their wings to take advantage of their experience they're unlikely to be be driving high-producing lines at this point in their careers.
Even looking at younger players and beyond Boston, how many examples are there of top 6 centres who are getting great performance out of wingers that normally aren't quite at that level or who are still 'emerging' talent? Genuine question because right now I can't think of any.