When Vikings players blamed this season’s poor second-half play on execution, they weren’t kidding.

This team even has trouble getting lined up correctly on offense.

Wide receiver Percy Harvin said Monday the offense twice lined up in the wrong formation on crucial third-down plays during Sunday’s 24-20 loss to the Tampa Bay Buccaneers.

The right plays could have resulted in “walk-in touchdowns,” Harvin said. The 0-2 Vikings desperately need those plays after getting outscored a combined 41-3 in the second half this season despite brilliant first halves against San Diego and Tampa Bay.

“We just have a couple meltdowns on third down,” said Harvin, whose Vikings face the 2-0 Detroit Lions on Sunday at the Metrodome. “We forget the formation, Donovan (McNabb) gets sacked, and then we have a busted play. But it’s us. It’s all us.”

When asked which players botched the formation, Harvin said, “I’m not getting into that…into the formations and who did what.”

The Vikings failed to convert two third downs on goal-line plays – McNabb’s low pass to tight end Visanthe Shiancoe late in the second quarter and the Bucs’ all-out blitz that disrupted a pass intended for running back Lorenzo Booker early in the fourth quarter.

McNabb also absorbed a third-down sack with 6:11 left in the third quarter.

Regardless, Harvin’s point was clear. The Vikings need to play smart football to have a chance.

As if the botched offensive plays didn’t fully illustrate the undisciplined start, Sunday’s eight penalties for 65 yards will suffice.

The Vikings’ 5-for-11 conversion rate on third down “ultimately determined the game,” Harvin said.

“It’s nothing physical,” Harvin said. “We’re not getting outworked blocking-wise. We’re fundamentally sound….We just had a letdown.”

Despite having several veterans on both sides of the ball, the Vikings still are learning to “mature as a football team,” coach Leslie Frazier said.

While urging not to discount “how well they’re playing in the first half,” Frazier said his team needs to find a way to finish.

Lack of execution, not strategy and second-half adjustments, is the problem, Frazier said.

“For us, we felt we had a good plan coming out of the second half,” Frazier said. “If you listen to and talk with anybody from the Buccaneers, I don’t think they’ll tell you they did a whole lot of things different than they did the first half. We didn’t do as good a job executing in some key situations, and that’s what you’ve got to be able to do. We’ve got to do a better job of playing situational football.”