There were clues.
The Chicago Bears offense was held to 17 or fewer points in each of the team's first three games, even though there were hints that the revamped unit could become special under new offensive guru/head coach Matt Nagy.
With second-year No. 2 overall pick Mitchell Trubisky playing quarterback sans training wheels in Nagy's new-look offense, Chicago's offense looked particularly effective early on against the Green Bay Packers in Week 1 and the Seattle Seahawks in Week 2.
It was an indication that Nagy was on to something with his offensive scripts, which might have made it all the more frustrating to see the offense struggle beyond the scripted portions of each game.
Trubisky completed 19 of 26 passes for 354 yards and six touchdowns (both career highs) in a turnover-free performance as the Bears crushed a hyped Tampa Bay Buccaneers team 48-10 on Sunday.
Fourteen of those points came on their first three drives of the first quarter. But this time, the Bears didn't slow down. They scored in all four quarters, and at one point they scored 31 consecutive points in the second and third quarters.
Trubisky became the first Bears quarterback in nearly seven decades to throw at least a handful of touchdown passes in one game. His 154.7 rating was, of course, the highest of his career. Aaron Rodgers has posted a higher rating only once in his career. Tom Brady has done so just twice.
Did it come against a bad defense? Certainly. The Bucs entered Sunday ranked last in football in terms of opponent completion percentage, 30th in opponent passer rating and last in passing yards per game allowed. That secondary is a mess. Veteran cornerback Brent Grimes appears to be out of gas, while experienced safety Chris Conte is injured, and the Bucs lack the depth to stay afloat under those circumstances.
But nobody is asking the Bears to score 48 a week. Instead, this is much-needed proof that they can do it on a good day against a vulnerable opponent, which probably means they can score 24, 27, maybe 30 on a decent day against a decent opponent.
When your defense features early-season MVP candidate Khalil Mack, as well as strong supporting cast members Akiem Hicks, Eddie Jackson, Kyle Fuller, Danny Trevathan, Prince Amukamara, Adrian Amos and Roquan Smith, that's probably all you need from Trubisky and Co.
The Bears needed to see that they could explode offensively against any opponent, but they also needed to confirm that they could shut down a strong opposing offense. That was also the case Sunday.
The Bucs had scored at least 27 points in each of their first three games. Their quarterback, Ryan Fitzpatrick, entered Week 4 as the highest-rated passer in the NFC, and they led the NFL with a yards-per-play average of 7.5.
But Mack and the Chicago defense held Tampa Bay to 10 points. They chased Fitzpatrick from the game at halftime with just nine completions and an interception under his belt. They limited the Bucs to 5.2 yards per play.
Mack had another strip sack and continues to be the league's top candidate for Defensive Player of the Year.
That was as large a statement as the one Nagy and Trubisky made, because that D surrendered 24 points to the Packers despite the fact that Green Bay was without a healthy Aaron Rodgers for much of the Week 1 tilt. They held the Seahawks and Cardinals to 31 combined points in victories, but both of those NFC West teams have struggled offensively.
The Bucs were wrecking defenses before they hit Soldier Field, but instead they were wrecked Sunday by a defense that now leads the NFL with 18 sacks and is second with eight interceptions.
Now, it's finally fair to declare Chicago a contender in the tough-as-nails NFC and the even tougher NFC North. They proved in Week 1 that they can go toe-to-toe with Green Bay on the road, and that was before Nagy and Trubisky found a groove. The Minnesota Vikings haven't earned a victory since Week 1 and have fallen 1.5 games behind Chicago, while the 1-3 Detroit Lions are two games back of the division-leading Bears.
It remains early, but October has arrived, and the Bears are rising, not fading.
They have a bye week next, and beyond that they have four consecutive games against teams from the soft AFC East. There's a good chance they'll win five or even six of their first eight games.
"It feels really good to sit here with a smile on my face," veteran offensive lineman Kyle Long said after Sunday's victory, per ESPN.com's Emily Kaplan. "For the last five, six years I've been saying, 'We're getting better, we're getting better, we're young. We're going to get there.' And you could see it. But now you guys get to see what I'm seeing. It feels good. The secret is out."
Trubisky was babied for much of his rookie season under John Fox, which was understandable considering that he started just 13 games at North Carolina. But Nagy is allowing the 24-year-old to spread his wings, and it helps that he's got the weapons.
His six touchdown passes Sunday were caught by five different receivers, three of whom—Taylor Gabriel, Allen Robinson and Trey Burton—weren't on the roster last season. And they lit up the Tampa defense despite getting only 25 yards on 11 carries out of top running back Jordan Howard, partly because Swiss army knife Tarik Cohen accumulated 174 scrimmage yards and a touchdown on 20 touches.
With Nagy's oversight and so much support on the field, there's lots of room for Trubisky to grow, and that loaded offense should only become more dangerous as he and his first-year head coach evolve in their respective positions.
Brad Gagnon has covered the NFL for Bleacher Report since 2012.