We were all guilty of it.
Then we watched one more football game and found out that we are a sports nation that jumps to conclusions and makes knee-jerk reactions.
Did everyone forget that the 49ers were the No. 4 overall defense in the NFL last season? Did everyone forget that the Colts were so bad that they earned the right to draft No. 1 in April?
Did everyone forget that Green Bay's quarterback is named Aaron Rodgers and Chicago's is still Jay Cutler?
Now that we all had a chance to find out how wrong we were about two teams after one week, let's take a look at some other conclusions we jumped to that may very well have been off base.
Peyton Manning looked "Super"
Relax. He looked good. He looked like an upgrade to Tim Tebow. He did not, however, look anything like the old Peyton Manning.
His ridiculous passer rating was helped by the fact that most of his passes were screens and intermediate routes. Add to that the fact that he was playing an aging Steelers defense that was without starting safety Ryan Clark.
Robert Griffin III is the second coming
I like RG3. I like him a lot. What I don't like is the attention he is getting after one win over a team missing its head coach, assistant head coach and defensive captain.
Like Manning, Griffin was eased into things with short, high-percentage passes designed to calm his nerves.
That pass to Garcon you've seen 1,000 times since Sunday came on his second series, was his seventh passing attempt, and to be honest, was not a great throw. Most of the credit should go to Garcon for making a nice catch and outrunning everyone to the end zone.
Again, I like RG3, I just can't stand how the media glorifies young athletes, essentially setting them up for failure. Let's at least hold off until Week 9 when he faces last year's version of RG3, Cam Newton, before we get this hype train rolling at full speed.
Chris Johnson is a bust, both in reality and fantasy
Pump the breaks. I was in Nashville for the game on Sunday. What I saw was a Titans team that had no other real weapons on an offense facing a retooled New England defense looking to make a name for itself. All they had to do was shut down Johnson. That didn't take more than a few plays, which then allowed the second- and third-tier defenders to focus on not letting Jake Locker get the best of them.
I saw flashes of greatness in rookie receiver Kendall Wright. Once they get Kenny Britt back, he, Wright and Nate Washington will form a solid trio of receivers and the Titans will have a passing game opposing teams will have to respect. That will open holes for Johnson to run the way he can, making us look foolish for writing him off.
The Ravens are world beaters
The Ravens are good. Are they better than last year, when they were a dropped pass from playing for the Lombardi trophy? I don't know.
What I do know is that we are making assumptions about a team based on one game where they beat a team who may have overachieved last season when they made the playoffs. By the way, Baltimore beat Cincinnati twice last year.
And why are we all so surprised that Joe Flacco can pass? Do NFL teams often draft FCS quarterbacks out of college to be game managers and hand the ball off?
The Ravens could very well make it as far into the playoffs as they did in 2011, but really, why would this surprise us?
The Jets proved us all wrong and look like an offensive powerhouse
Well, no. But they did beat an awful Buffalo team that picked up right where they left off last season, when they lost eight of their last 10 games.
Did you really think Buffalo's defense would be that much better after overpaying for a guy Houston was happy to let go?
Get back to me when the Jets put up 28, never mind 48, on Pittsburgh, San Francisco, Houston and New England...all before Halloween.