In the days immediately following a 16-10 loss to the Minnesota Vikings on Oct. 18, Chiefs coach Andy Reid stood in front of his team and addressed the players as a group.

They were seated in a big auditorium, several players remembered, and Reid — whose team was saddled with a 1-5 record, the worst start to a season in his 17-year head coach career — spoke with a passion they would not forget.

“He was saying, ‘I’ve never been with a team that’s 1-5,’ ” tight end Travis Kelce said. “But then he followed it with an energy, an enthusiasm, saying, ‘Now it’s a challenge.’ He presented that challenge for us right then and there and knew that our backs were against the wall.”

Reid addressed his team many times during the first six weeks of the season, likely with the same message. But this one struck Kelce.

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“I wouldn’t say the other (speeches) didn’t land,” Kelce said. “But this one was more urgent … (saying) ‘We’re one-third of the way through the season, we’re to the point where we need to turn this around right now.’ ”

In the weeks following the meeting, which preceded a 23-13 win over the Steelers that jump-started the Chiefs’ current six-game winning streak, Reid mentioned that the quality of practices have improved, and players agree, citing improved effort under a time-worn but true cliché of taking it one day at a time.

But NFL teams, of course, just don’t go from losing five straight to winning six straight, as the Chiefs have, by practicing harder.

There are real, fundamental football reasons for the Chiefs’ turnaround, much of which has to do with the tweaks they’ve made to their offensive scheme — both passing and rushing — after the reality of star running back Jamaal Charles’ season-ending injury set in.

“The defense was focusing on ‘We’ve got to stop Jamaal Charles,’ ” running back Charcandrick West said. “Now they’ve got to stop a team.”

Charles has been one of the NFL’s most-heavily used players during his time under Reid, averaging team-high 19 touches per game since 2013. So when Charles was lost for the season with a torn ACL in a loss to the Chicago Bears on Oct. 11, it was fair to wonder how the Chiefs would replace him.

But in the seven games since, the Chiefs are averaging 129 rushing yards per game, a total that would be the highest full-season total in the league and is a full 20 yards higher than they were averaging with Charles before his injury.

So what gives? The plays are the same, players and coaches say, but since their miserable start, there’s been an emphasis on calling the kind of running plays their young offensive line thrive on. Those tend to be inside power runs like isolation (iso) and inside zone, featuring plenty of double-teaming at the point of attack.

Now, a smart man would bet this philosophical shift probably would have happened even if Charles didn’t get hurt, but it just so happens that West and Spencer Ware — Charles’ replacements — are capable of using the type of one-cut running style that makes those plays effective.

“The play calls are a little bit different than Jamaal being out there, because he has a different skill set than Charcandrick and Spencer,” left guard Jeff Allen said. “Jamaal is a special player, everyone knows what he can do … but the offense now is definitely geared toward was Spencer and Charcandrick do best.”

And that’s running the football up the middle. According to NFL.com, the Chiefs rank third in the NFL with 15 runs of 10-plus yards up the middle.

“It puts defenders on their heels because you’ve got to make a decision quick, and with our line doing a great job, we’re able to find those small little creases,” Ware said. “We’re straight at them, man vs. man.”

Reid says he will continue to rotate the backs, but West, who is 5 feet 10 and 205 pounds, said he and Ware, who is 5 feet 10 and 228 pounds, have enjoyed forming their own “thunder and lightning” combo.

“I’m not a big guy, so defenses are expecting me to shake,” said the 5-foot-10, West said. “But with Spencer, they know (power) is coming.”

The increased emphasis on running the ball has also given the Chiefs’ offensive line the ability to wear down defensive fronts and slow down the pass rush, which was a problem earlier this season.

Through the Chiefs’ first six games of the season, the offensive line was a mess — especially in pass protection. During that span, the Chiefs yielded the third-most sacks in the league (24) and surrendered the eighth-most quarterback hits (36).

During the Chiefs’ next six games — all wins — they have allowed only 15 sacks and 26 quarterback hits. The line has finally started to jell.

“It’s been kind of neat to see them grow in different ways,” Reid said. “They all seem to get a little bit better as they’ve gone on. There’s been great communication, which is good.”

Tackle Laurent Duvernay-Tardif agreed, and pointed to better chemistry up front.

“I think before, we were talking a lot on the line of scrimmage, even sometimes over-communicating,” Duvernay-Tardif said. “Now we’ve simplified stuff, not in the way we play, but just in the way we talk about stuff. It’s just clear, everybody knows what they’re doing.”

Some of that not only has to do with simplified protection calls, but the steady hand of quarterback Alex Smith, who helps identify blitzes and set the protection at the line of scrimmage.

“He might change the protection to something that might put us in a better position ... he’s definitely been a leader throughout this whole process,” center Zach Fulton said. “We all like him, we all want to protect him.”

Smith said the frequency with which he’s allowed to audible out of plays or change the protection varies week to week, but his linemen will defer to him.

“Alex has the best seat in the house to see pressure and stuff like that,” Duvernay-Tardif said.

With improved protection — and an improved running game — in front of him, Smith has been able to spread the ball around while being more efficient with his downfield shots. While the Chiefs are second-to-last in the league on passing attempts that travel 21-plus yards in the air, Smith has completed 12 of 29 such passes for 383 yards and three touchdowns for a league-high passer rating of 123.1.

“I think for sure, we’ve been able to fall back on ‘With these two (backs), we’re gonna run the ball, we’re gonna play-action pass, (use a) possession passing game on first or second down and take our shots,” said Smith, who hasn’t thrown an interception in 2 1/2 months. “I do think, all around the field, it’s made us hard to defend, because you’ve got to pick your poison, right? When you’re running the ball, you get good looks outside.”

These last few weeks, defenses have struggled deciding where to put their focus. In a 30-22 win over Buffalo, the Bills opted to double Kelce, which left Jeremy Maclin open for a big game. And in a 34-20 win over Oakland, safety Charles Woodson followed Maclin around or shaded his way most of the time, which left Kelce and No. 2 receiver Albert Wilson open to make some plays.

“They can’t pick on one guy,” offensive coordinator Doug Pederson said. “Because the Raiders, for instance, would basically try and eliminate Jamaal Charles (before his injury). They would blitz him and cover with (Woodson). Well, now we’ve got two or three backs that are rotating, so what are you going to do? Who are you going to double? You can go after Kelce or Jeremy, but you can’t double both, and we’re aware of that.”

To be clear, no one is saying the Chiefs are better off without Charles. This growth in the offense could have come anyway, especially as the schedule eased up over the past six weeks, and his presence likely will be missed against tougher opponents down the road. But the offense was forced to mature without its bell cow, and that’s a good thing — especially when Charles returns next year.

“(Jamaal’s) such a dynamic player, he’s such a unique matchup, that for me, it was always easy just to, like, go back to that,” Smith said. “Like if you’ve got man (coverage), the best matchup on the field is Jamaal. So I think (his injury) made us have to be a little more, I don’t know, maybe a little more well-rounded?

“I mean, it was so easy to just always fall back to him because he was so good. We’ve had to spread all that around a little bit more now.”

It’s worked, and the success they’ve had the past six games would have been hard to predict in mid-October, when Reid met with his team and issued his urgent, “1-5” challenge after the loss of their best player.

But the message stuck, his players listened, and the strategic shift on offense has led to positive development on the ground and through the air that helped deliver them from the abyss.

“I really think he wanted us to get more shortsighted, more refined in all of our focus,” Smith said. “It’s easy when you’re there (1-5) for (this thing to) just tear itself apart … guys are pointing fingers, coaches and players, and it’s easy, really easy.

“It’s rare, I think, that guys kind of stay hunkered down, kind of keep preparing, keep putting in the time, because it is pretty dark at that point.”

But this was not an ordinary team, it turns out.

“We had enough guys in this locker room that had pride in what they do on this football field and in this locker room,” Kelce said, “so we just turned it around.”