Modern sports statisticians will tell you that two games is a "small sample size.'' But then so is a shot glass filled with arsenic.

The Vikings haven't just begun the 2011 with two losses, they've blown two games with poisonous second-half performances that call into question the ability of their coaches to adapt during games, their offensive philosophy, their choice of veteran quarterbacks and their ability to fulfill the lofty expectations of ownership.

Since 1990, only 12.5 percent of NFL teams that have lost their first two games of the season have made the playoffs, and we can probably make a leap of logic and guess that an even smaller percentage made the playoffs after getting outscored 41-3 in the first two second halves of the year.

The Vikings have begun a season in which they proclaimed themselves contenders and during which they are seeking approval for a billion-dollar stadium by treating the second half the way your average downtown office worker treats Friday afternoon. They've taken off early.

In the season opener, the Vikings led San Diego 17-7 at the half. Then the Chargers won the second half 17-0.

Sunday, in their home opener, the Vikings took a 17-0 first-half lead over Tampa Bay, and it was a lead built on physical domination along the lines and a bruising running game led by Adrian Peterson. After intermission, the Bucs outscored the Vikings 24-3.

"My first thought was, wow, we gave that game away,'' Peterson said.

Two losses may not seem consequential, but this is becoming a trend. Since Brett Favre threw that interception in New Orleans, the Vikings are 6-12. Since taking over for Brad Childress as head coach, Leslie Frazier is 3-5.

The Vikings have begun 10 previous seasons with two losses. They made the playoffs in just one of those 10 years (2008). They finished .500 or below the other nine times, and fired coaches during or after four of those seasons.

"I'm trying to find a positive word to use,'' defensive end Jared Allen said. "I really don't have one. So, I'm going to listen to my mom and not say anything at all.''

What left many in the Vikings' locker room in shock Sunday was that they have enough good players to take a lead and yet not enough leadership, or coaching, or nerve, to win. They build the deck, then forget to seal it.

"Offensively and defensively, we have a lot of talent,'' Peterson said. "But that doesn't get it done. It takes a will to finish.

"It's the second week in a row we let one get away. We've got a job that we need to finish.''

In two consecutive second halves, quarterback Donovan McNabb has put the arm in Armageddon. In San Diego, he threw for 2 yards in the second half. Sunday, he threw for 75 while again looking uncomfortable in the pocket and too often inaccurate.

Sunday, the Vikings rushed for 186 yards. Peterson gained 120 and two touchdowns while proving more adept than ever at reading blocks and making deft moves in the hole.

Again, his efforts were squandered by a passing offense whose origins may be found on cave walls. Although McNabb's numbers were hardly embarrassing, his only completion for more than 20 yards came on a screen pass that Toby Gerhart carried for 42.

Athletes and coaches are experts at downplaying losses. Their jobs require patience and a measure of optimism. A realist, though, now looks at their schedule and sees precious few victories and a division that may have passed the Vikings by.

This week, the Detroit Lions come to the Metrodome. The Lions beat the Bucs in Tampa; the Vikings lost to the Bucs in Minneapolis. The Lions won 48-3 on Sunday to improve to 2-0; the Vikings lost at home to drop to 0-2.

The Lions have built one of the best young NFL teams; the Vikings are clinging to a proud group of veterans who have kept ownership from recognizing that the roster needs to be overhauled.

What has to be more troubling inside the locker room is that Peterson's brilliance has positioned the Vikings to win two games, and the rest of the offense has squandered them both.

Jim Souhan can be heard Sundays from 10 a.m. to noon and weekdays at 2 p.m. on 1500ESPN. His Twitter name is Souhanstrib. •