Caps got beat by Montreal because they have awful goaltenders.
Pens got beat by Montreal because Fleury was awful for 5 of the 7 games.
During the 14 games they played so far , montreal had to play only 3 times against a goalie that was really good. ( 1 game Varlamov and 2 games Fleury)
The rest of the games they played ,the goalies always let at least 1 soft goal sometimes 2 or more. Last night , Fleury let in 4 goals on 13 shots and 3 of those 4 goals where very soft goals. Montreal had only 20 shots total and Pittburgh had 39. Halak was great as always and Fleury played like crap ( again ) . So there you have it. Now how about facing a great goalie Montreal ?
The other way to look at that is to say that Montreal capitalised on the weaknesses of the teams they've played. Montreal didn't get to where they are only because the goalies they've faced have been bad. They've done a better job of going to the net more, and their defence has been really connecting. They just shut down Crosby and co., and that's no easy thing to do.