For much of the last seven months, from the Patriots' improbable Super Bowl comeback win to all the offseason acquisitions that made them better, we were convinced that the 2017 version of this squad could rival the 2007 team that went 18-1, including a 16-0 regular-season record.

And perhaps, once it's over, that will be the case. But now, hours after the Chiefs dismantled the Patriots in Gillette Stadium, there's a lot of re-evaluating -- what happened, why it happened, and what if means going forward.

The Pats were favorites to win and win big (the spread was nine points) but there were signs that the Chiefs wouldn't just roll over. For starters, Tom Brady hasn't been his Hall of Fame self when Julian Edelman isn't on the field and that was the case again Thursday night. Brady completed just 44 percent of his passes with no touchdowns and three sacks.

"I just think we need to have more urgency and go out there and perform a lot better," Brady said after the game. "That is a winning attitude and a championship attitude that you need to bring every day. We had it handed to us on our own field. It's a terrible feeling, and the only people that can do something about it are in that locker room. We've got to dig a lot deeper than we did tonight because we didn't dig very deep tonight."

The bigger issue was New England's defense, which was abused all night by Alex Smith, Kareem Hunt and Tyreek Hill. The problems started when linebacker Dont'a Hightower left with a knee injury and continued right through the final whistle. Big-money free-agent acquistion Stephon Gilmore looked more like an undrafted rookie free agent, the lowlight coming on this blown coverage against Hill that resulted in a 75-yard touchdown.

When it was over, the Pats had allowed 42 points and 537 yards -- both low points in the Belichick era.

So how does the loss -- and the way it happened -- affect the Patriots' prospects of defending their Super Bowl title? CBS SportsLine's Stephen Oh explains:

The Chiefs' upset win had a big impact on the season forecast. The simulations were already high on Kansas City, having them No. 3 in the AFC at the season start, and their win projection went up from 9.2 to 10.2 and their chances of getting a No. 1 seed in the AFC jumped from 4.8 percent to 22.6 percent.

The Patriots' win projection dropped by -1.2 wins. Their chances of winning the Super Bowl are still more than double the next highest team but their chances did drop significantly from nearly 33 percent to 25 percent.

TOP 3 AFC (BEFORE)

WINS

PLAYOFFS

SEED1

CONFCHAMP

CHAMP

New England Patriots

12.5

99.0%

70.8%

48.4%

32.7%

Pittsburgh Steelers

10.3

78.7%

10.8%

15.3%

8.7%

Kansas City Chiefs

9.2

58.6%

4.8%

9.9%

5.7%

AFTER LAST NIGHT

WINS

PLAYOFFS

SEED1

CONFCHAMP

CHAMP

New England Patriots

11.3

95.5%

40.1%

38.3%

24.9%

Pittsburgh Steelers

10.3

77.3%

16.5%

17.8%

10.5%

Kansas City Chiefs

10.2

76.2%

22.6%

15.5%

8.6%

For the glass-half-full Pats fans: Hey, your team is still the favorite to represent the AFC in the Super Bowl!

That said, New England's defense is a disaster. And if Smith can pick them apart like he's Dan Marino, this is good news for the Steelers, who historically struggle against the Pats but also have the league's most potent offense.