He started to emphasize more on D than scoring. Plus we didn't have the same caliber of players as last year. They spent too much time trying to get Hossa.
The Pens got hot down the stretch after getting Hossa, getting the #2 seed in the East (the day they got him, they were a point behind New Jersey for the division title), going 12-2 against the three East playoff opponents, and he had 26 points that playoff.
Also, they didn't lose a home game for nearly four months.