Linebackers Sam Acho (94) and Clark Haggans (53) help shut down the 49ers in the second half of a December game last season, a big moment for the defensive unit.
Bad-field position, a poor transition on a punt and one single play, covering 37 yards as Frank Gore scampered for a touchdown at University of Phoenix Stadium, didn't put the Cards in a great spot.
But it felt like, more than any other, when the defense arrived.
The Cardinals' defense had already been playing better by then, making key plays when it was needed and leading the Cards into what turned into a season-closing hot streak. Yet this particular situation may have been the watershed moment. Suddenly down 19-7 to the best team in the division, a team that had just clobbered the Cards, 23-7, a few weeks previous.
There were six San Francisco possessions after Gore's touchdown. The 49ers ran a grand total of 19 plays, for a mere 51 net yards (10 of those from a penalty) and one measly first down. The defense allowed the offense time to score two touchdowns, and come up with a victory.
As linebacker Clark Haggans chased 49ers quarterback Alex Smith into the game-clinching fourth-down incompletion, there had to be a realization of what could be.
The Cards will go into 2012 with some offensive weapons and their chance to win the NFC West likely hinges with its quarterback play. But the team will be anchored by a defense that, in theory, will perform well enough to make most games within reach.
Talking to defensive players throughout the offseason – whether it was veterans like Adrian Wilson, Darnell Dockett or Kerry Rhodes or even younger players like Patrick Peterson and David Carter – there is clearly a confidence in the system of defensive coordinator Ray Horton that wasn't there at this time last year. It couldn't have been, with the lockout and the inability to really know what was going on.
By the time the season was over, the Cardinals were the most difficult team upon which to convert third downs. They were the second stingiest when it came to allowing touchdowns within the red zone. And over the last nine games of the season – when the players finally "got" what Horton was trying to do – the unit was top five in the NFL in multiple categories.
Sure, there are places of caution. The Cards must see if cornerback William Gay fits as well as Richard Marshall did a year ago. There are some high-powered offenses, like the Patriots, Eagles, Packers and Lions, dotting the schedule. Young players like linebackers Sam Acho and O'Brien Schofield must perform.
The Cardinals have also talked a few times about creating more turnovers. The team only had 10 interceptions last season. What was amazing about their late season run was that it was frequently less about game-changing plays and just steady work to force a ton of punts (which, when Patrick Peterson is the guy running them back, isn't such a bad thing.)
But, assuming health, it's difficult not to feel the optimism the players themselves do.
It's been a while since the defense was the unit upon which the Cardinals relied on the most. The playoff team of 1998 had the young defensive line. Once Kurt Warner arrived, offense was leaned on, although when Ken Whisenhunt first showed up the ultimate dream was to have a Steelers-type of aggressive domination defensively.
What's interesting is that the entire NFC West has morphed into defense-first. The 49ers have built their renaissance on defense and the Seahawks are trying to do the same. Jeff Fisher's first version of the Rams is supposed to as well, and it makes sense given the blueprint of how Fisher's Titans used to look.
The Cardinals have no problem being in that mix.
"Every year is different," Horton said earlier this offseason. "I know our guys well now, I understand what we can and cannot do, I understand where we need to improve at. … How do we use that great base we had and start the way we finished and keep going up?"
Locking down teams like it did against San Francisco last December will be a start – and go a long way in setting up the Cards' potential success.
