Toffoli leaving did open a guaranteed top6 spot for Meier, but I think he was already playing with Hischier & Bratt while Toff was here, might have been on pp2 unit though.
I think it's mostly just him not being 100% and being a very streaky scorer. Playing RW helps, but the way he's playing right now looks like he could play any position. Last season when he scored 40, majority of those were scored inside 3 month or so. I think he went scoreless for the first 10 games and had just 'decent' production after being traded to nj. Nothing like we're seeing now where he seems to score every night.