The Kansas City Chiefs’ Week 5 win over the the Houston Texans was significant for several reasons. It squashed any lingering doubts about who the NFL’s best team is, as the league’s only 4-0 team moved to 5-0. It also solidified KC’s place atop our NFL projections, as we now give them a 97 percent chance of making the playoffs and an 81 percent chance of earning a coveted first-round bye. But perhaps the team’s most impressive achievement so far is this: These are the best Chiefs since KC’s last (and only) championship team, 48 years ago.

Using Elo, our pet metric for judging a team’s strength at any given moment, we can trace the various incarnations of the Chiefs week by week in NFL history. Their current Elo rating of 1701 is the highest it has been since the team hit its all-time peak rating of 1775 after defeating the Vikings in Super Bowl IV. Of the 899 weeks for which we have Elo data on this team, there are only eight in which Kansas City’s rating was higher than it is right now — and all of them came in that 1969 campaign, in the last year of the AFL. Move over, Len Dawson, make room for Alex Smith.

But we have certainly seen hot starts from Andy Reid’s team before. They started the 2013-14 season 9-0 and then lost five of their next seven regular-season games before bowing out to the Indianapolis Colts in the AFC Wild Card game. So will this year be any different?

The defense has regressed since the 2013 season, surrendering 22.2 points per game through five games, compared with 19.1 for the whole of the 2013 season. But they’ve maintained respectability despite losing star safety Eric Berry, who went down for the season with a torn Achilles tendon in the team’s opening-night road win over the New England Patriots. And any step back here has been more than compensated for by improvements on offense. Led by Smith and rookie running back Kareem Hunt, the offense is off to a blistering pace, averaging an NFL-best 32.8 points per game, 5.9 points better than the 2013 team managed to produce.

This may be hard to digest, but Smith is having one of the best starts to a season of any quarterback in NFL history. In almost every major offensive category — passing completion rate, passer rating, adjusted yards per attempt and interceptions — Smith ranks among the best. Here are the best season-opening five-game stretches ever, according to passer rating, among QBs who made more than 150 passing attempts in that span in any season since 1950.

In addition to having the fourth-best passer rating in this time frame, Smith has yet to throw an interception. And among these quarterbacks, Smith’s completion rate of 76.6 percent is the highest. The table above puts Smith in some nice company: Every QB joining him is either a Hall of Famer already or will likely be one soon — with the exception of Daunte Culpepper. (And unlike Culpepper, Smith doesn’t have the luxury of being able to heave jump balls to Randy Moss.) In this group, Culpepper and Smith also stand out as the only ones to not start at least one Super Bowl in their career to date. Culpepper may be alone in that regard after this season.

In the Pitts

Kansas City’s Week 6 opponent had a slightly less glorious Week 5. In fact, the Pittsburgh Steelers suffered one of the worst losses in their 85-year history. Ben Roethlisberger threw five interceptions in a brutal 30-9 loss at home to the Jacksonville Jaguars (yes, them). The Steelers’ loss was so bad that they dropped 55 Elo points, the 49th-worst single-game drop in more than 30,000 NFL games, and the franchise’s third-worst loss ever. Steelers fans may not want to remember the two worse losses, but we’ll remind them anyway: a 24-6 defeat at home to the newly formed Houston Texans in 2002 and a 34-10 thumping on the road against the previously winless Cincinnati Bengals in 1979 (ouch!).

The latest loss means Roethlisberger is under intense pressure to retire, with even the two-time Super Bowl winner admitting that he might not have it anymore. That, along with the quarterback’s public spat with wide receiver Antonio Brown in Week 4, means the Steelers could be in a minor crisis. Pittsburgh finds itself 3-2 and atop the AFC North standings, with the Baltimore Ravens and Cincinnati Bengals lurking just behind. Looking at the underwhelming slate of opponents the Steelers have played so far — the Cleveland Browns, Minnesota Vikings, Chicago Bears, Baltimore Ravens and Jacksonville Jaguars — gives even more cause for concern. The Steelers travel to the Chiefs next week before a home game against their bitter rivals the Bengals and a visit to the surprisingly good Detroit Lions. The rest of October could alter Big Ben’s plans in 2018.

FiveThirtyEight vs. the crowd

Week 5 in our NFL prediction game — in which we invite you to pick football games and try to outsmart our Elo algorithm — was much better for you readers than the previous two weeks had been — readers were just 21 points behind the Elo predictions in Week 5 compared with 146.2 points behind in Weeks 3 and 4 combined. The readers made gains mostly by being less wrong than our algorithm. Both Elo and the readers picked the Oakland Raiders to beat the Ravens and the New York Giants to beat the Los Angeles Chargers, and neither of those picks worked out. However, the average reader was less confident in either the Raiders or the Giants of winning than Elo was, so readers lost fewer points on those misplaced bets.

The biggest net gain for Elo came in the Miami Dolphins’ win over the Tennessee Titans. Even without factoring in that the Titans’ Marcus Mariota was inactive for the game, Elo put its faith in Jay Cutler and the Dolphins and was rewarded. (Never doubt Jay Cutler! Haha, no, we’re kidding. Definitely doubt him.) That’s it for this week — be sure you make your picks for Week 6.