One of the things about the Sens during this playoff run aside from Karlsson's dominance is that they basically added two top-6 forwards for free---one would be Clarke MacArthur, when he returned from his concussion hiatus, and the other is Bobby Ryan. I mean, sure, a guy named Bobby Ryan may have been physically present for their regular season, but he's gone from looking like one of the worst cap albatrosses in the league to a guy that's actually worth his cap hit in the playoffs.
Then there's Pageau, who went from a fairly solid, two-way third-line center in the regular season, to scoring at a 50-goal pace in the playoffs. And Derick Brassard has also stepped his game up fairly substantially, after it was looking like the Sens lost the Zibanejad/Brassard trade pretty handily in the regular season.
Even though they haven't had the toughest road so far, they're full value for where they are, and they're not going to be an easy out for the Pens. We'll just have to hope that the Pens can get some good goaltending, and that Crosby, Malkin & Kessel can go beast mode for long stretches.