The easiest example is how would a line do against McD/Girardi and Staal/Stralman? Would that same line do better or worse against Klein/Moore? Assume that other teams' equivalent of McD/Girardi and Staal/Stralman went up against Stepan's and Richards' lines. That leaves the equivalent of other teams' Klein/Moore defensive pairing against Brassard. I think it's natural to expect that with the same amount of minutes the production would decrease as the forward line moves up to play against tougher defensemen. It should be a bit of a concern since Brassard is mostly out there to put up points.
Staal/Stralman was one of the best second pairings in the league. I don't think the jump from 3rd line defenders to 2nd line defenders is extreme enough to warrant a significant problem. Beyond that, this is assuming that their line last year only went up against 3rd line pairings.
Zuke went up against similar competition (marginally tougher competition and marginally tougher zone starts) and put up near 60 points. Brass did well against his competition, but not well enough that i'm confident he'll flourish in 2nd line situations.
Brassard will still have MZA on his line. I guess Brassard didn't help Zuccarello score those points? I would be surprised if Brassard didn't score 50+ points this year. If he does that he would've rank 35th among centers in points last year.