For what it's worth, I don't think we can any longer compare the success of the 97-98 playoff team with anything the Cards do from last year forward.
Why, you ask? Because the 97-98 team benefited from a great, last-place schedule. We played just awful, awful teams the entire season, and just squeaked into the playoffs with a last-second field goal. Place this against following "outhouse to penthouse" teams like the 98 Falcons, 99 Rams, 00 Ravens, and 01 Pats. The Rams and Pats won their divisions with soft schedules, and the Ravens went to the wild card going away in a pretty tough division (expansion Browns notwithstanding).
What has changed? Expansion and re-alignment created a new, balanced schedule which means that there are only two "at large" games each season, as opposed to the 8 in the pre 2002 era. Each team in a division plays 14 common opponents now (6 home/away games in division, 4 against in-conference division, 4 against out-of-conference division), and that means that it's going to be a lot harder for teams to go from cellar to stellar in a year with a good FA period and good draft.
It's a whole new ballgame for the Cards now, and that means that we're going to have to build a good team and stay good, because we're not going to get any relief in the division from a soft schedule.