Buchnevich extended the lead to 5-1 with another power-play goal at 4:19 of the third.
Maenalanen, playing his ninth NHL game, cut it to 5-2 at 11:51 but DeAngelo scored 1:04 later to make it 6-2.
"Opportunities are there for us every night and to not come through with the two points that we wanted, that we came here to get, yeah, it's disappointing, it stinks," Carolina captain Justin Williams said. "We don't have the luxury of having those games certainly with where we're at."