"Behind Enemy Lines" is a Thursday post on the Access Vikings blog. In advance of Sunday's Vikings-Cardinals game, Dan Wiederer of the Star Tribune interviewed Kent Somers, the beat writer for the Arizona Republic. Here are three things you need to know ...

1Ryan Lindley best stay loose.

A week ago, the rookie out of San Diego State was Arizona's third-string quarterback. Now he's one big hit away from playing. And the Cardinals offensive line has been giving up plenty of big hits on their quarterback recently.

In the past three games, Arizona has allowed 22 sacks. In last week's loss to Buffalo, Kevin Kolb suffered a severe injury to his ribs, which moves John Skelton back into the starting quarterback slot.

Vikings defensive ends Jared Allen and Brian Robison face favorable matchups.

"These elite pass rushers have just been killing the Cardinals," Somers said. "Even last week, [Buffalo's] Mario Williams, who hadn't done anything all season, gets himself two sacks. Arizona gave up five sacks last week, and it was considered progress."

As for Skelton, Somers calls him "erratic."

"He misses some really, really easy throws a lot. He's a young guy who's up and down and often struggles with his accuracy."

2 Arizona's 4-0 start was propelled by its energetic defense.

The Cardinals have yet to allow more than 21 points in a game and rank fourth in the NFL in scoring defense (16.2 ppg). They also have 13 takeaways, fifth best in the league.

End Calais Campbell and tackle Darnell Dockett have been terrific.

"Campbell has been a handful for everybody," Somers said.

Somers also said inside linebacker Daryl Washington "is playing at a Pro Bowl level" right now.

3 The Cardinals running game has serious issues.

Beanie Wells is on injured reserve because of a toe problem. And Ryan Williams suffered a season-ending shoulder injury in Week 5.

Next man up? William Powell got the most carries last week and ran for 70 yards on 13 carries against Buffalo. LaRod Stephens-Howling, more of a third down back, was limited to 22 yards on 11 carries.

Powell is 5-9 and 205 pounds and actually showed a few signs of promise last week.

Said Somers: "He's pretty quick and he makes good cuts. So he's been a recent pleasant surprise. We'll see."

"Behind Enemy Lines" is a Thursday post on the Access Vikings blog. In advance of Sunday's Vikings-Cardinals game, Dan Wiederer of the Star Tribune interviewed Kent Somers, the beat writer for the Arizona Republic. Here are three things you need to know ... 1. Ryan Lindley best stay loose. A week ago, the rookie out of San Diego State was Arizona's third-string quarterback. Now he's one big hit away from playing. And the Cardinals offensive line has been giving up plenty of big hits on their quarterback recently. In the past three games, Arizona has allowed 22 sacks. In last week's loss to Buffalo, Kevin Kolb suffered a severe injury to his ribs, which moves John Skelton back into the starting quarterback slot. Vikings defensive ends Jared Allen and Brian Robison face favorable match-ups. "These elite pass rushers have just been killing the Cardinals," Somers said. "Even last week, [Buffalo's] Mario Williams, who hadn't done anything all season, gets himself two sacks. Arizona gave up five sacks last week and it was considered progress." As for Skelton, Somers calls him "erratic." "He misses some really, really easy throws a lot. He's a young guy who's up and down and often struggles with his accuracy." 2. Arizona's 4-0 start was propelled by its energetic defense. The Cardinals have yet to allow more than 21 points in a game and rank fourth in the NFL in scoring defense (16.2 ppg). They also have 13 takeaways, fifth best in the league. End Calais Campbell and tackle Darnell Dockett have been terrific. "Campbell has been a handful for everybody," Somers said. Somers also said inside linebacker Daryl Washington "is playing at a Pro Bowl level" right now. 3. The Cardinals running game has serious issues. Beanie Wells is currently on injured reserve with a toe problem. And Ryan Williams suffered a season-ending shoulder injury in Week 5. Next man up? William Powell got the most carries last week and ran for 70 yards on 13 carries against Buffalo. LaRod Stephens-Howling, more of a third down back, was limited to 22 yards on 11 carries. Powell is 5-foot-9 and 205 pounds and actually showed a few signs of promise last week. Said Somers: "He's pretty quick and he makes good cuts. So he's been a recent pleasant surprise. We'll see."