As the Vikings defense continues to have difficulties stopping teams late in games, it's hard to blame the defensive line and linebackers because this group is playing with one of the worst secondaries in team history.

The Vikings have been outscored 71-44 in the fourth quarter of their nine losses this season. In only two games has the defense held a team scoreless in the fourth quarter -- their 33-27 loss to Green Bay and the 27-21 loss to Oakland last week. And in that first loss to the Packers, the defense couldn't get the ball back at the end of the game.

Teams have marched right down the field with quick rhythm passes late in several games. The Vikings defense could have won several games with some stops late. In the season opener at San Diego, which the Vikings lost 24-17, the Chargers outscored them 10-0 in the fourth quarter. The next week against Tampa Bay, the Vikings were outscored 14-3 in the fourth quarter and lost 24-20. In Week 3 against Detroit, the Lions outscored the Vikings 16-3 in the fourth period and overtime and won 26-23.

Yes, quarterbacks have been having their way with the Vikings pass defense lately.

In the 24-14 loss to the Falcons on Sunday, Matt Ryan completed 27 of 34 passes for 262 yards and three touchdowns for a quarterback rating of 128.2.

Last week, the Raiders' Carson Palmer threw for only 164 yards, but he completed 17 of 23 passes and threw for a touchdown for a rating of 107.9. Two weeks ago, the Packers' Aaron Rodgers, who figures to be the NFL MVP, completed 23 of 30 passes for 250 yards and four touchdowns for a 140.3 rating.

While there was concern about the ability of the secondary when the season started, nobody expected it to be this unproductive. Certainly one problem is the number of injuries the unit has suffered.

The Vikings are tied for 27th in the NFL with only six interceptions, and their 2,840 passing yards allowed ranks 29th.

Last season, then-defensive coordinator Leslie Frazier said the group of Antoine Winfield, Cedric Griffin and Chris Cook made up one of the best groups of cornerbacks in the league. What a difference a year makes.

The 34-year-old Winfield is still viewed as one of the league's top corners, but he managed to play in only five games this season and is now on injured reserve because of a broken clavicle.

Griffin, a second-round pick in 2006, has had a hard time coming back from torn anterior cruciate ligaments in both knees. He hasn't registered a single interception this year.

Cook was viewed as a future standout for the Purple when he was drafted in the second round last year, but he took care of his Vikings career with his personal problems off the field.

The weakness of the secondary is one big problem facing Rick Spielman, Scott Studwell and company as they try to retool for 2012.

Harvin shines What a show Percy Harvin put on Sunday, catching eight passes for 95 yards, returning a kickoff for 104 yards and rushing five times for 11 yards.

Harvin has been gaining yards for the Vikings at a record pace. Last season he set the franchise record with 3,992 net yards in his first two seasons, breaking the record held by Adrian Peterson, who had 3,922 yards in 2007 and '08.

With Sunday's performance, Harvin has amassed 5,176 net yards in two seasons and 11 games. The career record for net yardage by a Vikings player is 12,410 by Cris Carter, but Harvin is already nearly halfway to second place, which is held by Darrin Nelson at 10,365 yards. It took Nelson 10 seasons to reach his total and Carter 12, leaving Harvin well on pace to break the Vikings record.

Jottings • When Frazier and his staff review the film of Sunday's loss to Atlanta, they are going to be sorry they didn't throw the challenge flag to review Harvin's third-and-goal run late in the game, because even the announcers were certain it was a touchdown.

• On Monday morning, Eden Prairie football coach Mike Grant will meet with the school athletic director and let him know he is going to return as coach for the 2012 season and hopes to add to the six state championships he has won. Of course, Grant is the school's athletic director as well. He said he figures the Eagles should be strong again. ... Grant had nothing but good words to say about Wayzata coach Brad Anderson, who has won three state titles, adding that he believed Eden Prairie's 13-3 victory in the Prep Bowl was a game that either side could have won.

• Grant described running back Andrew Larson, who scored a big touchdown Friday night and ran for 1,097 yards and 16 touchdowns this season, as the best football player he has coached. And that is saying something considering Grant's son Ryan, now a Gophers linebacker, never lost a game in high school as a quarterback and defensive player. Mike Grant said he is surprised that more Division I colleges aren't recruiting Larson.

• That was Matt Knoff, son of former Vikings safety Kurt Knoff, who as a starting safety for Eden Prairie made a big interception on the 2-yard line Friday. And playing defensive end for Eden Prairie was Anthony-King Foreman, the son of another Vikings player in Chuck Foreman.

Sid Hartman can be heard weekdays on WCCO AM-830 at 6:40, 7:40 and 8:40 a.m. and on Sundays at 9:30 a.m. • shartman@startribune.com