When the Chicago Bears traded for Khalil Mack, it looked like a long-term investment in their rebuilding plan.

Who knew it was also a win-now move?

Had the Bears made one of about a dozen plays in Week 1 at the Green Bay Packers, they’d be 4-0. Still, 3-1 doesn’t look too bad on them. The Bears were perhaps the most impressive team of Week 4, destroying the Tampa Bay Buccaneers 48-10. The Bucs have their issues on defense, but it was still a 2-1 team with wins over the Saints and Eagles. The Buccaneers didn’t look like they were in the Bears’ class.

Before the season the Bears looked like a team that was still early in its rebuild, and might be an exciting breakout team in 2019. Perhaps we overlooked the signs of a potential breakout this season, and it seems like their start is based on a solid foundation:

• The Bears are a defense-first team. That type of squad is usually predictable from week to week. They had a good defense last season and were set to return 10 starters with rookie top-10 pick at linebacker Roquan Smith being the only new face. Then right before the season started the Bears added Mack, who has been the best defensive player in football so far.

Everyone knew the Mack addition would be a big one, but it has been better than expected. The Bears look like a top-five defense across the board with no real weakness, and that probably isn’t going to change. Getting a fierce pass rush without blitzing too much gives Chicago a major edge.

• Because Matt Nagy was a rookie coach, it was tough to accurately assess how big of an impact he would have. Maybe he hasn’t had a Sean McVay-level impact, but it has been significant.

Nagy has had his rookie moments, like most of the second half of Week 1, but he has been solid. It seemed Sunday like the Bears are grasping his offensive ideas. Chicago had open receivers all day against the Buccaneers. And maybe it’s not that Nagy is great yet, but the previous staff was holding the team back. The Bears and John Fox were a bad marriage from the start, and we might not have factored in what a big upgrade this staff was.

• The Bears did a good job upgrading the offensive talent around quarterback Mitchell Trubisky. Trubisky had no chance last season with the lack of talent around him. Mostly the Bears’ moves have all worked out. Allen Robinson doesn’t look all the way back to his 2015 form, but he’s a solid No. 1 option. Taylor Gabriel, another free-agent addition, had 104 yards and two touchdowns on Sunday. Tight end Trey Burton was an expensive gamble after he played well in a limited role with the Eagles, but he has been a great fit. He has scored in two of Chicago’s last three games.

The Bears needed to add multiple pieces to the offense in the offseason, and credit the front office for identifying which players would fit and being aggressive to land them.

• The quarterback might be the biggest wild card for the Bears the rest of the season.

Trubisky was great on Sunday. Before that, he was inconsistent. This is just life with (most) young quarterbacks. Some weeks Trubisky will be very good. Maybe not six-touchdown good, but he has talent. He’s also working on consistency, and perhaps his accuracy will keep him from being great. Because we’re so early into his career, the ups and downs will be a little more extreme. The Bears defense has bailed him out before (see Week 3 at Arizona), but it’s hard to depend on that. Unless what we saw Sunday was a true coming-out party, there will likely be weeks in which Trubisky struggles and the defense can’t overcome it. That’s part of the equation for the Bears and it lowers their ceiling.

Nobody expected the Bears to do too much this season. But four weeks in, it’s hard to deny what they’ve done. It will still be hard to overcome the Vikings and Packers over the rest of the season, but it’s also possible those teams aren’t as good as we expected. Even if this isn’t a full breakout for the Bears this season, the arrow is pointing up. Chicago probably isn’t going anywhere for a while.

Story continues

Here are the power rankings after Week 4 of the NFL season:

32. Arizona Cardinals (0-4, Last Week: 32)

Rookie quarterback Josh Rosen didn’t light it up, but he played pretty well for a first start. As a whole the Cardinals looked better, and a game at San Francisco next week gives them a decent shot at a win.

31. San Francisco 49ers (1-3, LW: 31)

C.J. Beathard threw for 298 yards and a pair of touchdowns, including a long one to blossoming tight end George Kittle. Most teams play well in their first game with a new quarterback after the starter gets injured, and the 49ers did play pretty well in a loss at the Chargers. The challenge is keeping that effort level up, especially at 1-3.

30. Buffalo Bills (1-3, LW: 28)

Ah, there are the Bills we saw in Weeks 1 and 2. They lost 47-3 in the opener, were behind 28-3 in Week 2, lost 22-0 in Week 4 at Green Bay and … absolutely blew out the Vikings in Minnesota a couple weeks ago. I still don’t get what happened in that Vikings game, and probably never will.

29. New York Jets (1-3, LW: 27)

It’s common to get a Week 1 result that doesn’t match up with anything else we see in Weeks 2-17, and this year’s wonky Week 1 game might have been the Jets’ win. They looked tremendous that night and have been bad ever since. It’s not a huge surprise because there’s a long way to go in this rebuild. But the opening-week hope that they might be a surprise team this season is long gone.

28. Oakland Raiders (1-3, LW: 30)

Through four games, tight end Jared Cook has 26 catches for 370 yards and two touchdowns. He was the Raiders’ best player on Sunday. We’ve been waiting for Cook to play like this seemingly forever, and strangely enough his breakout seems to be happening at age 31.

27. Cleveland Browns (1-2-1, LW: 26)

Did the Browns get cheated on the reversal of what would have been a game-clinching first down? Maybe. There was not enough evidence for a reversal in my opinion, but it was a close call. Still, when you’re punting to a team with no timeouts, leading by eight points, with 1:38 to go, you still should win. Reversal or not, the Browns had plenty of chances to finish and couldn’t get it done.

26. New York Giants (1-3, LW: 24)

The Week 3 win over the Texans looks like the outlier for the Giants’ offense. In their other three games they have 15, 13 and 18 points. The 18 points Sunday, which included a late touchdown and two-point conversion after they fell behind by 16, came against a Saints defense that hasn’t been very good this season. Saquon Barkley, a healthy Odell Beckham and new coach Pat Shurmur were supposed to fix the offense, but that hasn’t happened yet.

25. Houston Texans (1-3, LW: 29)

If Colts coach Frank Reich had punted, the story with the Texans would likely be that they blew a 28-17 fourth-quarter lead and still be winless, and we’d probably been hearing calls for Bill O’Brien’s job. A lot of people in Houston should feel lucky this week that the heat is on Indianapolis for how Sunday’s game ended.

24. Detroit Lions (1-3, LW: 25)

I still don’t know how the Lions could let Ezekiel Elliott beat them, especially on the last drive after they took a lead. The Cowboys have nobody else on offense. The difference between the Lions winning that game and getting back to .500 after an 0-2 start, and blowing it in the final minutes, seems bigger than it should for Week 4.

23. Indianapolis Colts (1-3, LW: 21)

I love coaches who are risk takers. For too long the NFL has acted like going for it on fourth-and-1 at midfield was like hitting on 20 in blackjack. But there’s being bold and being reckless, and going for it on fourth-and-4 in your own territory late in a tied overtime game is on the reckless side of that line.

22. Atlanta Falcons (1-3, LW: 19)

Matt Ryan’s last two games: 55-of-74, 793 yards, eight touchdowns, zero interceptions, 144.7 passer rating. The Falcons have lost both games. If you’re still citing quarterback record as a real stat, you believe Ryan is an 0-2 quarterback the past two weeks. Let’s stop using a quarterback’s record like it’s a legitimate thing.

21. Dallas Cowboys (2-2, LW: 23)

The Cowboys are going to have to be in the trade market for a receiver. Ezekiel Elliott had 240 yards on Sunday and he’s a fantastic talent, but eventually opponents are going to give him the Rob Gronkowski treatment and refuse to let him beat them. Dallas is tied with the Eagles, right behind the 2-1 Redskins for first place. But they aren’t a serious contender without some help for Dak Prescott.

20. Seattle Seahawks (2-2, LW: 22)

For a moment let’s forget the drama surrounding Earl Thomas’ injury and the middle finger to the sideline on Sunday. Football-wise, it’s a brutal injury for Seattle. Never underestimate how great of a player Thomas is. Now the Seahawks, who Sunday barely beat a team most would consider the worst in the NFL, move on without a Hall of Fame-level talent at safety. That’s a tough loss.

19. Denver Broncos (2-2, LW: 13)

That pass Case Keenum missed to Demaryius Thomas in the final seconds, when Thomas was running wide open down the sideline, is going to stick with him a long time. Denver is not a patient place when it comes to quarterbacks, and Keenum isn’t off to a wonderful start.

18. Tampa Bay Buccaneers (2-2, LW: 16)

Dirk Koetter said Jameis Winston “probably” did enough to earn the start for Week 6, after the team’s bye next week, though it wasn’t Ryan Fitzpatrick’s fault the Buccaneers lost on Sunday. The Fitzpatrick story was great, but it has always been in the best big-picture interest of the franchise to start Winston.

17. Pittsburgh Steelers (1-2-1, LW: 15)

Whatever we want to say about Le’Veon Bell or the Steelers or how either side handled it, this is where we are: The Steelers gambled on giving Bell another one-year deal, assuming he would make it easy on them and play all season, and they’d have no long-term commitment after that. They lost that gamble because their one-dimensional offense is not the same without Bell.

16. Miami Dolphins (3-1, LW: 9)

I didn’t want to put the Dolphins even as high as ninth last week, but you can’t justify putting one of three 3-0 teams too low. But if you want comedy, remember that the Dolphins were trailing 38-0 with less than 100 yards of total offense in the fourth quarter, and then look how mad the Dolphins fans were last week when I said I didn’t think they weren’t a top-five NFL team. Funny stuff.

15. Washington Redskins (2-1, LW: 18)

Washington is in first place and here’s its (fairly easy) schedule the next few games: at Saints, vs. Panthers, vs. Cowboys, at Giants, vs. Falcons, at Buccaneers, vs. Texans, at Cowboys. If Washington can split the next two, the six games that follow aren’t too daunting. Keep that in mind and don’t be too shocked if we see an 8-3 Redskins team traveling to the Eagles for a big Dec. 3 showdown.

14. Tennessee Titans (3-1, LW: 20)

It’s not surprising, once his quarterback looked like he could throw the ball again, that Corey Davis had a big game. He has supreme talent and an injury-filled 2017 season didn’t change that. He’ll have plenty more games like his 9-161-1 performance Sunday, which he capped with a phenomenal game-winning touchdown catch.

13. Minnesota Vikings (1-2-1, LW: 8)

The Vikings will get things turned around. Kirk Cousins has been very good (again, let’s dump the whole “quarterback record” thing; it’s a team sport) and the defense didn’t forget how to play football. But they also can’t afford to wait, especially since it doesn’t seem the Bears are going anywhere.

12. Cincinnati Bengals (3-1, LW: 14)

Don’t forget the Bengals put up 37 points and got a big road win without Joe Mixon, who looked great to start this season. Giovani Bernard is one of the best backups in the league so there wasn’t much of a dropoff there, but having Mixon and Bernard will make one of the NFL’s surprising teams even better.

11. Los Angeles Chargers (2-2, LW: 11)

Aside from one half at Buffalo this season, the Chargers haven’t played anywhere near their talent level. They should not be grinding out a two-point win at home against a 49ers team without Jimmy Garoppolo. We’ll see what happens next, but it’s hard to be too optimistic after what they’ve done so far.

10. New Orleans Saints (3-1, LW: 12)

It hasn’t been pretty but after four games the Saints are in good shape. And Mark Ingram returns after a four-game suspension. Alvin Kamara is a great player but Ingram provides the depth that was lacking. Unlike other teams, the Saints got through their rough patch early this season without much damage in the standings.

9. Chicago Bears (3-1, LW: 17)

In a weird scheduling quirk, the Bears have four games in a row against the AFC East after their bye. The good news is the AFC East stinks, and the one tough game against the Patriots is in Chicago. I’m not expecting the Bears to win all four, but it’s not entirely crazy either.

8. Baltimore Ravens (3-1, LW: 10)

On Sunday night, 11 different players caught a pass for the Ravens. Last season, and probably the season before, the Ravens barely had a handful of capable offensive players around Joe Flacco. Give credit to the Ravens’ front office for being aggressive and reshaping the offense. It’s paying off.

7. Green Bay Packers (2-1-1, LW: 7)

If you’d have taken an informal vote after one week, presumably everyone would have predicted Aaron Rodgers to win MVP. And he still might. But through four weeks, he has 1,130 yards, seven touchdowns and one interception — nothing wrong with that, but not exactly Rodgers-esque numbers given the explosion of passing stats this season. There’s a reason Rodgers wasn’t too pleased after beating the Bills 22-0 (which also says something about the Bills that a 22-point win was disappointing).

6. Carolina Panthers (2-1, LW: 5)

It’s from last week but it should be repeated as often as possible: The story of Panthers defensive end Efe Obada, the Week 3 NFC defensive player of the week, is the best in the NFL this year. It’ll make a great movie someday.

5. New England Patriots (2-2, LW: 6)

Just 10 catches and 105 yards for Rob Gronkowski the past three weeks. That’s usually a good day for him. Gronk hasn’t fallen off, but it’s clear teams won’t let him beat them. Julian Edelman’s return this week might open some things up.

4. Philadelphia Eagles (2-2, LW: 3)

They’re a fourth-down play in overtime from being 3-1, so it’s not like the Eagles are crumbling. But it’s not a surprise that a team that went 16-3 including playoffs is experiencing some regression. The Eagles will be fine, just not the runaway train they were most of last season.

3. Jacksonville Jaguars (3-1, LW: 4)

Leonard Fournette’s health is becoming a big issue. He had ankle problems at LSU and again last season. This year it’s his hamstring. He missed some time, then it tightened up on him Sunday early in his return and he had to leave the game. Not every second-year player who has had some bad luck with injuries is destined to be nagged by injuries his whole career, but it’s concerning with Fournette.

2. Kansas City Chiefs (4-0, LW: 2)

Patrick Mahomes looks like he’s going to be the face of the NFL for the next decade. I’m not sure what else can be said about him. Watching him next week against the Jaguars’ great defense is going to be phenomenal.

1. Los Angeles Rams (4-0, LW: 1)

It has been a while in these power rankings since the gap between the No. 1 and 2 team has been so large. There’s no realistic case you can make for any other team being No. 1. That doesn’t mean the Rams will win a Super Bowl, but this is the clear class of the NFL about a quarter of the way in.

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Frank Schwab is a writer for Yahoo Sports. Have a tip? Email him at shutdown.corner@yahoo.com or follow him on Twitter!

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