As everyone said, team had a superior higher end but was too soft and easy to score against. (In the East, only the Islanders and Ottawa were worse defensively.) They were a bit like the L.A. Kings c.1991-1994.
Zubov did well. Possibly a guy they should have held onto.
Overall goals-for vs. against, Lemieux was +84 and Jagr +103. Lemieux 79 points on the power-play (in 70 games), Jagr 51. That's half of Lemieux's points and nearly a third of Jagr's. Maybe they were a bit overly reliant on the power-play for goals? And, as we know, in 90s'-era NHL the refs often put those whistles away in the playoffs.
(Checks.) Indeed, the stats show that the Pens scored about half a goal per game more than the average team because of their awesome power-play. I would guess in the playoffs that advantage was taken away.
They were also trending downward as that season progressed. On January 5th, they beat the 1st-overall Red Wings and their record was 26-10-3 (.705). The rest of the season, they went 23-19-1 (.547).