DENVER -- While the Denver Broncos celebrated Sunday, Kansas City Chiefs quarterback Patrick Mahomes walked away with the disappointment, frustration and regret showing on his face.
Instead of leading his teammates to a pivotal win in dramatic, comeback fashion, Mahomes had just finished the game, a 28-24 collapse of a loss, on his backside. The Broncos sacking Mahomes on the game's final play was a perfect punctuation to one of the Chiefs' most embarrassing losses under coach Andy Reid. After going up 11 points deep into the second half, the Chiefs lost the lead -- and their lead in the AFC West -- to the Broncos with an error-filled performance in the fourth quarter.
"The execution just wasn't at a high enough level," Mahomes said. "We made big plays, and we made plays happen against a really good defense, but you've got to execute for the full 60 minutes. We weren't able to do it."
Prior to Sunday's game, the Chiefs were 80-2, including the playoffs, when they led by 10 or more points in the fourth quarter with Mahomes as their starter.
"You can't dwell on it," tight end Travis Kelce said. "Obviously in our hearts we felt we should've come out with a victory, but that's not the reality of things. We've got to fix a lot. We just didn't finish the way we should've."
The Chiefs (5-2) went scoreless in the final 15 minutes. Meanwhile, the Broncos (6-2) scored 15 points on their final two drives. Sunday's game was the Chiefs' largest fourth-quarter point differential in a loss under Reid, who became their coach in 2013.
Just about everything that could go wrong for the Chiefs did in their collapse. Reid made several conservative decisions, including punting early in the fourth quarter on a fourth-and-inches near midfield. The Broncos then marched 80 yards on nine plays to cut the lead to three points.
The Chiefs' next possession ended in an even worse outcome. Facing a third-and-2 from the Broncos' 30-yard line, Mahomes made his biggest mistake of the game. Instead of throwing the ball away when his three pass-catching options were covered, he was sacked by linebacker Alex Singleton for a 6-yard loss. The play set up a 54-yard field goal attempt for kicker Harrison Butker, who missed it wide right.
"I can't put [Butker] in that position," Mahomes said. "Obviously, we're in field goal range, in a big moment, and I'm trying to make a play. Their defense played well. They passed off [their zone] coverage really well. I've got to throw the ball away or get vertical. Whenever you're on the edge of field goal range, you don't want to move backward because it puts [Butker] in a tough spot."
Reid did have another option, especially with Butker's struggles this season when kicking long field goals. According to NFL Next Gen Stats, a punt would have given the Chiefs the highest win probability ahead of going for it (74.3% vs. 72.5%). A field goal attempt, however, ranked last (71.5%). ESPN Analytics metrics also disagreed with Reid's decision to have Butker attempt the 54-yard kick (73.4% win probability) instead of punting (76.8%).
"It's within Harrison's range," Reid said of his decision.
Butker's miss continued his ongoing woes. Since the start of last season, Butker has missed 16 kicks -- 11 field goal attempts and five extra point attempts -- the most by any kicker in the NFL during that span.
"It was just a really bad miss," Butker said. "I just completely missed the ball and didn't even give it a chance. It didn't feel good off the foot."
Two plays later, the Broncos scored the go-ahead touchdown, a 5-yard touchdown run by Jonah Coleman, who set up the score with a 51-yard catch-and-run the play before.
In all, the Broncos needed less than five minutes to score the decisive touchdowns Sunday, highlighting the part Kansas City's defense played in the collapse. The unit pressured Broncos quarterback Bo Nix on only two of his 34 dropbacks (6%), the lowest pressure rate by any team in a game this season.
"It's only one thing, rush the passer, get the quarterback down," pass rusher Chris Jones said. "We blocked a couple of balls, but I don't think we got [Nix] down. I put that on the D-line. We've got to win our one-on-ones. We've got to take advantage of that. We got a one-on-one, we got to win it."
Speaking after the game, Reid identified a different area of concern: penalties. The Chiefs finished Sunday with a season-high 11 penalties for 105 yards, including a 15-yard roughing penalty by Alohi Gilman on Denver's first touchdown drive of the fourth quarter. On the season, the Chiefs have been penalized for 164 more yards than their opponents, the largest margin in the league. So of course it was a penalty that nullified their would-be game-winning touchdown on fourth-and-goal from the 1-yard line with four seconds left. On the play, Mahomes found Rashee Rice in the middle of the end zone, but right tackle Jaylon Moore was flagged for a false start penalty. On the next play, Mahomes was sacked by defensive end Malcolm Roach to end the game.
"We ran a really good play that we liked a lot," Mahomes said of his pass to Rice. "You kind of showcased that play. We talked about that play [in] the meeting the night before [the game]. It gets a lot of attention on Travis and then you hit Rashee underneath.
"We had to go to a different play [for] that last one, and they covered it well. Whenever you get that close, and you don't capitalize, you take that on yourself and you learn from it. I wish I'd done a better job of getting the ball out, just giving somebody a chance. It's fourth down."
If the Chiefs had beaten the Broncos, they would've taken a commanding lead in the division. With a win, the Chiefs would've had an 86% chance to win the division crown, according to ESPN Analytics. Following Sunday's game, the Broncos now have a 52% chance to win it.
"Now you're kind of in a dogfight for the division," Mahomes said. "You just try to get better and better, so that at the end of the year you're playing your best football."