PBR - Last night's loss knocked the Phillies to 12 games below .500, a mark they haven't been at since 2000.

If you guessed one you're correct.
Taking out the four clubs impacted by strike-shortened seasons (94 ATL, 94 SFG, 81 NYY, 81 KC), every club except the 1986 Cardinals finished with a record above .500. As a matter of fact, the 30 clubs averaged 95 wins in the season following their respective 100 win campaigns (the '86 Cards finished 79-82).
In franchise history, prior to the 2011 club, the Phillies had two other teams that finished with at least 100 wins: 1976 and 1977. Obviously, the '77 club finished above the .500 mark, and the '78 version finished 90-72.