As you might expect, Montreal exceeded their expected shooting percentage and save percentage by the largest amount in the second round, scoring at a 35.7% higher rate and stopping shots at a 25.6% higher rate than we would have expected given shot locations and rebounds.
Note that Montreal actually had the lowest expected shooting percentage for - so the Habs shooters were doubly-good at making their shots in the 2nd round given that they were furthest away from the net, on average, of any team.
In particular, the Habs exceeded expectations at even-strength:
Pittsburgh's expected shooting percentage was poor, but Montreal's was abysmal. But when it was all said and done, Pittsburgh shot just 3% at evens, while Montreal substantially exceeded expectations.
On the power-play, other teams saw big jumps:
Boston had the fewest PP shots in the second round (just 33; Montreal was the next-lowest, with 43) but they managed five PP goals to lead the round in PP shooting percentage. Pittsburgh also did well on the PP, picking up eight goals vs 6.4 expected, while Detroit underperformed by a similar amount. PP shooting percentage has a bit more uncertainty in it - not only because there are fewer PP shots, but also because we don't know if the PP was 5-on-4 or 5-on-3.