Fans who were couch potatoes watching NFL games on television Sunday got a chance to do some amateur scouting on the Detroit Lions' next six opponents.

They had expert company. With the Lions on a bye, head coach Jim Caldwell caught at least part of games that featured the team's next two opponents, the Pittsburgh Steelers and Green Bay Packers.

What we learned from those two games – and throughout the day Sunday – is something that Caldwell and other coaches preach constantly. Whether because of injury or performance, or a combination of both, things can change fast in the NFL. 

"It's week to week in this league," Caldwell said at his Monday press conference. "One week you play well, everybody thinks you're great. One week you play poorly, and they think you're terrible.

"That's why we play the games. You can't predict what happens. That's what makes our league interesting."

Here's what we learned – and in some cases confirmed – about the Lions' next six opponents in order from Sunday's TV scouting assignment:

Pittsburgh Steelers: The Steelers dominating 29-14 win over the Bengals indicates a tough first test is ahead for the Lions on Sunday night at Ford Field. The Steelers are rolling on offense behind Ben Roethlisberger, Le'Veon Bell, Antonio Brown and a strong line, and steamrolling quarterbacks on defense. The Steelers of old are headed to Motown.

At Green Bay Packers: No surprise, but the team the Lions will face on Monday Night TV is not the same with Aaron Rodgers out with a broken collarbone and Brett Hundley in at quarterback. The Packers ran for 181 yards in a 27-16 loss to the Saints at Lambeau Field, but there was no passing game. Hundley completed 12 of 25 passes for 87 yards, with a passer rating of 39.9. This should be a winnable game for the Lions.

Cleveland Browns: A 12-9 overtime loss to the Titans shows we can expect the expected from the Browns. Quarterback chaos continues, with rookie QB DeShone Kizer benched again in favor of Cody Kessler. So does losing. The Browns are 0-7.

At Chicago Bears: If we thought the Lions' 52-38 road loss to the Saints was as weird as it gets, we learned there is more to come, including at the opposite end of the spectrum. The Bears gained just five first downs, got four pass completions in seven attempts from rookie QB Mitchell Trubisky – and beat the Panthers, 17-3.
Rookie defensive back Eddie Jackson's two TD returns of a fumble and interception gave the Bears' defense all the points it needed to overcome the lack of offense.

Minnesota Vikings:In a space of three hours we learned how quickly the power has shifted in the NFC North. The Vikings' 24-16 win over the Ravens put them in first place alone with a 5-2 record. The Packers fell out of a tie for first, dropping to 4-3.

What the Vikings can bring to the table – sorry for the pun – on Thanksgiving Day at Ford Field in their rematch of a 14-7 Week 4 loss to the Lions is a defense capable of carrying the team, as long as the quarterback manages the game and doesn't commit turnovers. For now, that's what Case Keenum does.

At Baltimore Ravens: Once among the toughest teams in the league on both sides of the ball, we learned what injuries and free-agent losses mean on an offensive line. The Ravens gave up six sacks and their pass rush never got to Keenum in Sunday's loss. What was projected to be a rebound year after missing the playoffs the last two years is looking like a rebuild.

Bottom line:If we learned a lesson Sunday how things change fast, then we shouldn't forget that they can change again.