Mitchell Trubisky and the Bears have reason to celebrate. (Nam Y. Huh/Associated Press)

So often in the NFL, perceptions that appear obvious one week seem obsolete the next. On Sunday night last week, the New England Patriots were dismantling the Green Bay Packers, staking their claim as one of the league’s elite, a four-member club that also included the New Orleans Saints, Los Angeles Rams and Kansas City Chiefs. This Sunday, they were crumbling in Tennessee, absorbing a 34-10 thumping that clouded the rest of their season. This is not a league for definitive conclusions.

The Saints, Rams and Chiefs all won again Sunday. They remain the class of the league, and the Patriots, despite their ugly loss in Nashville, are still hovering close by. Next Monday night’s showdown in Mexico City between the Rams and Chiefs will only further ensure that the league revolves around the teams at the top. But New England’s humbling provided a reminder that nothing in the NFL should be written in pencil, let alone ink.

In Week 10, three teams declared themselves challengers to the group of elites, as threats to crash a conference title game. The NFL’s first tier may still be clear, but there’s another set of teams closing in. The Pittsburgh Steelers, Los Angeles Chargers and Chicago Bears are in close pursuit.

The Steelers opened the week with a demolition of the Carolina Panthers. Thursday night games make for difficult evaluation, but Pittsburgh’s offensive dominance in a 52-point outburst was too striking to ignore. In 2018, the most reliable path to victory is having an offense that can outscore the opponent in a shootout. The Steelers have that, even without Le’Veon Bell.

Antonio Brown, Ben Roethlisberger and Bell’s one-time understudy, James Conner, give Pittsburgh one of the NFL’s best trios. The power of the Steelers' attack rests in their offensive line, which has been together for several seasons and plays like it. It might be the best offensive line in the NFL, and it will allow the Steelers’ offense to perform anywhere, in any weather, come January. It may not be enough to win in, say, Kansas City, but it will give them a chance.

Then again, the AFC path to the Super Bowl may end up going through Los Angeles. The Chiefs have established themselves as the best team in the AFC, but they still haven’t been able to shake the Chargers in the race for the AFC West. But Kansas City already has a victory in Los Angeles, which probably will prove decisive in the race for the division title and a first-round bye.

But after smacking the Raiders, 20-6, the Chargers are 7-2 and riding a six-game winning streak that has them within range of the 9-1 Chiefs. For Kansas City, playing the Rams isn’t just a measuring stick. It’s a necessary game to keep pace in the AFC West.

It’s hard to find a more talented team than the Chargers. Philip Rivers, at 36, might be having the best season of his Hall of Fame career. Keenan Allen is a metronome of a wideout, and on the other side, Tyrell Williams is a dangerous deep threat. Melvin Gordon is Todd Gurley lite, which is a tremendous compliment. The Los Angeles defense is built perfectly to win in 2018: Multiple players can turn in game-shifting plays. Melvin Ingram, Joey Bosa (once he’s healthy) and Derwin James are all capable of making them. The kicking situation is a mess and Coach Anthony Lynn remains a wild card, but the Chargers could beat anybody without it constituting a surprise.

Could you say the same thing about the Bears? It’s not as ridiculous as it seems, primarily because Mitchell Trubisky is not the quarterback most people think he is. In his second season, and his first under Coach Matt Nagy, Trubisky has undergone a transformation. He still makes too many mistakes and he needs to be more accurate, but Nagy and Trubisky have worked around those deficiencies to make Trubisky an asset, no longer a quarterback that Chicago’s excellent defense must overcome.

The Bears played at home Sunday against the Lions, who are playing like a team that has packed it in, but Trubisky’s performance in a 34-22 victory was head-turning: He completed 23 of 30 passes for 355 yards and three touchdowns with no interceptions. No. 1 wide receiver Allen Robinson, Chicago’s biggest offensive addition in the offseason, returned from injury and caught six passes for 133 yards and two touchdowns. Rookie Anthony Miller, a preseason darling who has been emerging, added five catches for 122 yards and a touchdown.

“I thought Mitch had his best game of the season, without a doubt,” Nagy said at his postgame news conference. “He was on fire. He was efficient. He threw the ball with conviction. His eyes were great. He played confident, and I like that. Laser focus today — not that he hasn’t had it before, but you could just see it. And you could feel it.”

Even through his most cringeworthy moments this season, Trubisky has been more valuable than anyone thought thanks to his running ability. ESPN’s QBR metric, which takes running into account, rates him as the fourth-best quarterback in the NFL, behind only Drew Brees, Patrick Mahomes and Rivers. That seems a tad ambitious, but Trubisky really might be a quarterback capable of leading a team deep into January — at least a team that has Khalil Mack and one of the league’s top secondaries on the other side of the ball.

The Bears are 6-3 and probably even better than that record indicates. They have outscored opponents by 94 points. The Saints’ scoring margin is plus-98; the Rams are at plus-104. The Washington Redskins are also 6-3, but they’ve achieved that record, and first place in the NFC East, while outscoring opponents by a single point.

Next week, the Bears face the second-place Minnesota Vikings in a potentially decisive NFC North matchup. For now, they pose the biggest threat to the Rams and Saints in the NFC. But this is the NFL, so that could change quickly.

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