There are subtle improvements, significant upgrades and enormous enhancements. And then there are 73-point, early-game swings.

Got the Broncos figured out yet?

In their previous game at Invesco Field at Mile High, the Broncos fell behind the Oakland Raiders 38-0 midway through the second quarter. In their next home game, Sunday against the AFC West-leading Kansas City Chiefs, the Broncos went up 35-0 with 5:48 remaining in the second quarter.

From 38 down to 35 up. The Broncos finished off the Chiefs 49-29, a victory impressive enough to perhaps temporarily quiet the outrage outside the team’s Dove Valley headquarters and raise hopes within it.

“We wanted to play better in the first half, but we’ve been focusing on playing our best football in November and December,” said Broncos quarterback Kyle Orton, who threw a career-best four touchdowns on his 28th birthday. “And now we’re in November. This doesn’t fix all of our issues, but this is certainly a good start.”

The lopsided score, and how Todd Haley perceives the leading team should approach play in a lopsided score, got the Chiefs coach pointing mad. As Broncos coach Josh McDaniels stuck out his hand for the postgame handshake, Haley stuck out his right index finger and delivered a lecture.

McDaniels didn’t quite catch what Haley said, which is apropos because McDaniels has yet to read the unwritten rules of blowout etiquette.

When a team is up 35-0 early, the 49-29 final score is a nail-biter by comparison.

One solid game, even one great half, and the Broncos can believe again. They can believe in the weapon that is Tim Tebow, the rookie quarterback who ran for a 1-yard touchdown and threw for a 3-yard touchdown — on his first NFL pass attempt.

They can believe, at long last, that with the offensive line back to full strength, Knowshon Moreno can have a 100-yard rushing game. Moreno finished with a career-high 106 yards.

They can continue to believe in Orton, who was sharp early, throwing touchdown passes to Moreno, Brandon Lloyd and Jabar Gaffney in the first quarter. Orton added his fourth TD pass to the seemingly unguardable Lloyd in the fourth quarter.

Afterward, Orton credited his offensive line, which for the first time since the summer lined up, from left to right, with Ryan Clady, Zane Beadles, J.D. Walton, Chris Kuper and Ryan Harris.

“I’m telling you, I wasn’t even close to being touched the whole game,” Orton said. “I felt as comfortable today as I have in a long time.”

Denver’s D can believe that, given leads of 21-0 and 35-0, it can stop any rushing attack, even one that had been ranked No. 1.

“You get them out of what they do best,” said Lloyd, who continues to be the fantasy league surprise of the season. “You get them into a game where they’re going to throw the ball. That’s not what they do best. What they do best is jam it down your throat and let (Jamaal) Charles go crazy on the defense.”

The victory allows the Broncos to believe it’s not their home fans that give them the heebie-jeebies.

“We owed them,” said linebacker Mario Haggan, who had three sacks, three quarterback hits and two tackles for losses.

After going five weeks without reassurance, the Broncos can believe they are good enough to beat an NFL team, again. Even a first-place team.

“I don’t think there was the negativity people think there was,” said Harris, who returned to his starting right tackle position. “I think that was evident in the way we played together today and the way we won.”

And now the Broncos, even with their still-disappointing 3-6 record, are only two games back of the AFC West lead with seven to play. They can believe the division can be won.

“That’s got to be the motivation because everybody wants to play in the tournament at the end of the year,” Lloyd said. “As rough as the first half of the season was, and we still have a chance? That’s motivation.”

Mike Klis: 303-954-1055 or mklis@denverpost.com