The good news for the Pittsburgh Penguins right now in terms of their line combinations is that by loading up their three best offensive players at the moment (Sidney Crosby, Evgeni Malkin, Rickard Rakell) they have at least given themselves one trio that can potentially take over a game.
That unit has spent the past three games together and outscored teams by a 4-0 margin (and 5-0 for the season), and pretty much carried them to wins over Anaheim and Montreal this past week.
The bad news is that by loading up their three best offensive players on one unit they have pretty much cannibalized whatever scoring depth they might have had on the roster.