Nobody knows anything about the NFL in 2023.

Two weeks ago, the San Francisco 49ers were the best team in football. It wasn't even a question. There were no warning signs or reasons to believe they were anything but the NFL's most complete, dominant team.

But like the rest of the league this season, it all just changed for no real reason. The 49ers lost as a big favorite in Week 6 at the Cleveland Browns, who had backup P.J. Walker at quarterback, and then in Week 7 they lost again as a big favorite. This time it was the Minnesota Vikings, who were 2-4 coming in and took it to the 49ers.

Kirk Cousins, whose poor record on Monday nights has been mocked for years, had an excellent game and led a huge 22-17 win in Minneapolis. Brock Purdy had two chances for a game-winning drive in the fourth quarter but couldn't come through either time, throwing a pair of interceptions, including one with 25 seconds left. The win gets the Vikings to 3-4 this season.

The 49ers still are one of the NFL's best teams but weird back-to-back losses means they're vulnerable, just like everyone else.

Kirk Cousins shines on Monday night

Adding to the randomness of Monday night's Vikings upset, it was led by Cousins, whose teams were 2-10 on Monday nights coming in. Suddenly Cousins, playing without injured superstar receiver Justin Jefferson, was carving up the 49ers' respected defense.

Cousins has been the subject of trade speculation, but the Vikings are far from dead at 3-4 in a bad NFC. He was at his best on Monday night, throwing for 378 yards and two touchdowns against an excellent defense and doing so without one of the NFL's best players to throw to.

The Vikings played well in the first half, then hit an enormous play in the final seconds before halftime. Cousins threw a pass that was almost intercepted, but rookie Jordan Addison wrestled it away, turned upfield and had a 60-yard touchdown. The Vikings led 16-7 after that.

It was an awful call by 49ers defensive coordinator Steve Wilks. It made little sense with 16 seconds left and the Vikings on their own 40 to send a Cover 0, all-out blitz, considering the only thing that was going to hurt the 49ers was a deep pass. According to Next Gen Stats, it was the first seven-man rush in the final 30 seconds of a half in opposing territory since Week 11, 2020.

The NFL is usually determined by thin margins, and the 49ers gave away a touchdown.

Brock Purdy throws 2 picks

The 49ers got outplayed much of the night but were still in the game in the second half. The Vikings settled for a field goal after two failed attempts at a "Tush Push" from the 1-yard line and a misfire by Cousins into the end zone. McCaffrey scored his second touchdown of the game after that and the 49ers trailed 19-14.

The 49ers and Vikings traded field goals after that and the Vikings held a 22-17 lead deep into the fourth quarter. The 49ers had a couple of shots to win it. But with 5:30 left Purdy overthrew Jauan Jennings and Vikings safety Camryn Bynum picked it off. It's the kind of error that will fuel Purdy's critics.

San Francisco still had one more shot when Vikings kicker Greg Joseph missed a 50-yard field goal wide right with 1:11 to go. It could have been Purdy's redemption. The 49ers got into Vikings territory in the final minute. But Purdy, in a desperate situation, threw another interception to Bynum and the game was over.

The 49ers were on top of the NFL world two weeks ago. The Vikings were 1-4, had just lost Jefferson to a hamstring injury and were probably closer to trading everyone away than thinking about the playoffs. Two weeks seems to be an eternity in the NFL this season. More than ever, nothing is permanent.