In a season so far in which many of the league’s teams have been very good one week and very bad the next, no team has fit into that category any more than the defending NFC champion Cardinals. Coming off one of their biggest regular-season victories in years against the Giants on a national stage, the Cardinals staged an embarrassing turnaround Sunday against a Carolina team that they flat-out embarrassed in the playoffs last season.

What has really raised the eyebrows of daily team observers is that the team has excelled on the road, winning all three of its games up to now and looking good doing it, but has been a major disappointment at home, falling to 1-3 at University of Phoenix Stadium after their 34-21 loss to the Panthers, who entered the Valley Sunday as 10-point underdogs. In each of the past two seasons under head coach Ken Whisenhunt, the Cardinals finished with a 6-2 record at home. So far this season, they have played only one decent half of football at home — in their lone home victory vs. Houston.

The PFW spin

So what happened Sunday? “We just didn’t bring our A game,” said QB Kurt Warner, who deserves an “F” after registering five interceptions and a fumble, which ironically is exactly what Panthers QB Jake Delhomme did in the Cardinals’ stunning upset playoff victory in Carolina last season. One thing that is pretty clear is that, for the Cardinals to bring their “A game” on offense, they need a healthy Anquan Boldin in the mix. And for the past three games, Boldin, who left Sunday’s game in the third quarter after reaggravating an injury to his right ankle, clearly has not been close to 100 percent.

With that being the case, it has made it easier for opposing defenses to use safeties to help defend star WR Larry Fitzgerald, who just hasn’t been nearly as big a big-play threat so far this season as he was last season. Fitzgerald’s longest catch so far this year is only 27 yards, with his yards-per-catch average dropping to 10.8 (the lowest of his career) from an outstanding 14.9 yards average last season. With Fitzgerald often being covered like a blanket and Boldin limping along at less than full strength, Warner has been forced to throw more check-downs to his running backs — a trend that the opposition appears to have started figuring out.

Boldin’s availability for the game at Chicago was in question early in the week, so more new wrinkles might have to be added to the team’s offensive repertoire. And it goes without saying that the protection has to be better, especially from OLT Mike Gandy, who was treated rather rudely by Panthers DRE Julius Peppers on Sunday.

As for the defense, it’s a lot more difficult to explain what went wrong against the Panthers. Not only were the Cardinals unable to force a single turnover against the Panthers and Delhomme, who has been a turnover machine since his playoff debacle last season. It also allowed the Panthers to rumble for 270 yards and gain 6.1 yard per carry after entering the game as the league’s No. 1 unit against the run. One thing that was clearly evident was shoddy tackling across the board, and major improvement will be necessary this Sunday against the Bears.

It also will be imperative that Cardinals second-year CB Dominique Rodgers-Cromartie, who has been either brilliant or very vulnerable so far this season, to play a lot smarter than he did on the 50-yard hitch pattern that Panthers WR Steve Smith turned into a touchdown on Sunday. 

If the Cardinals stay true to their 2009 form, they probably will clean up their act this Sunday and give the Bears a real run for their money at Soldier Field. But they blew a golden opportunity to really take charge of the NFC West yesterday with the Niners losing on the road to the Colts, and that has to be a really hard pill to swallow.