Paul Connors, Associated Press
Arizona Cardinals wide receiver Larry Fitzgerald, left, is run down by San Francisco 49ers linebacker NaVorro Bowman, right, following a reception by Fitzgerald in the fourth quarter of an NFL football game Sunday, Dec. 11, 2011 in Glendale, Ariz. The Cardinals won 21-19.

TEMPE, Ariz. — Given up as a lost cause seven weeks into the season, the Arizona Cardinals have won five of six to climb within a game of .500.

Consecutive victories over Dallas and San Francisco have stamped Arizona's resurgence with legitimacy.

If the Cardinals win out, they will have a winning season and maybe even make the playoffs.

It's a turnaround based on defense and big plays, as well as the steady hand of coach Ken Whisenhunt, who reminded everyone after Sunday's 21-19 victory over San Francisco that he and his team never wavered from their approach in the six-game slide that left the Cardinals 1-6.

"I'm proud of our guys, the way they have played, and the way they have hung together after facing a lot of criticism," Whisenhunt said at his Monday news conference. "That's tough, in this league and today's NFL, everyone is going to have a media outlet or a form to make judgments about your players and your team, and that is a tough environment. A lot of times that will fracture your team, but our guys believed in it and stuck together."

The victory over San Francisco, a week after the 49ers clinched the NFC West title, came without Arizona quarterback Kevin Kolb, who went out with concussion-like symptoms on the Cardinals' third play of the game after taking a knee to the head.

Kolb will be evaluated under the strict NFL concussion rules through the week before it's determined whether he can play Sunday against Cleveland.

Backup John Skelton, who was so bad in the team's Nov. 20 23-7 loss at San Francisco that he was benched after three quarters, came on and, after a slow start, threw three touchdown passes.

But this victory belonged chiefly to the Cardinals' ever-improving defense. San Francisco had the ball inside the Arizona 10-yard line three times in the second quarter and managed only field goals. In the second half, the 49ers had two first downs, one on Frank Gore's 37-yard touchdown run that put them up 19-7 early in the third quarter, the other on an unnecessary roughness penalty.

Of the 20 plays San Francisco ran in the second half, 10 went for positive yards.

"There wasn't any bickering or yelling, we just said we were going to win the game in the fourth quarter," defensive tackle Darnell Dockett said. "We knew it was going to come down to the fourth quarter."

In the last six games, the Cardinals defense has allowed six touchdowns.

The win over the 49ers was Whisenhunt's 42nd as Arizona's coach, tying him with Don Coryell for most in the franchise's history. Whisenhunt said center Lyle Sendlein gave him one of the game balls after the contest.

"It was very meaningful that our team did that," the coach said, "but it's a team game, so we are worried about focusing on Cleveland this week."

Arizona, in the midst of playing four of its last five at home, hosts the Browns on Sunday, plays at Cincinnati on Christmas Eve day, then finishes its regular season at home against Seattle on Jan. 1.

The playoffs remain a longshot. The Cardinals (6-7) trail Detroit and Atlanta by two games. Dallas and the New York Giants share the NFC East lead at 7-6, so one of them could get the wild card nod. Chicago also is 7-6.

But playoffs aside, just having a winning season "would be incredible," Whisenhunt said.

"It would be very significant for the character of our football team," he said.