KANSAS CITY, Mo. -- Travis Kelce sat alone in front of his Arrowhead Stadium locker after most of his Kansas City Chiefs teammates had cleared out Sunday night. The veteran tight end had his head buried in his hands, as if he were trying to understand how the normally high-scoring Chiefs had been held to 13 points by the Indianapolis Colts.

In truth, there were many reasons the Chiefs were knocked off their game and held to their lowest point total -- by far -- since Patrick Mahomes took over as the starting quarterback last season. The 19-13 loss dropped the Chiefs to 4-1 and supplanted the previous low of 26 points set with a 12-point win over the Arizona Cardinals last season.

Here's how the Colts were able to make it work:

Ball control. Indianapolis put pressure on the Chiefs by keeping possession for more than 37 minutes, running 74 plays and scoring on five of their nine drives, not including one at the end of the game when they were running out the clock. That was a similar formula to the one used against the Chiefs by the Detroit Lions in Week 4, but the Colts executed better. They pushed the Chiefs around up front in rushing for 180 yards.

"I've got to get the bigs playing better," coach Andy Reid said, referring to not just the defensive front but also the offensive line. "It starts there. When you win, it starts there. When you lose, it starts there, too."

Kansas City's margin for error is slim because of its considerable defensive weakness, the most glaring part of which is the consistent inability to stop the run. When the offense doesn't play well, as it didn't against the Colts, the Chiefs are in big trouble.

Constant pressure on Mahomes. The Chiefs did a lousy job of protecting Mahomes, who was sacked four times and hit on several other occasions.

"We didn't block well," tackle Mitchell Schwartz said. "Your offense can't function when the O-line doesn't do their job. It doesn't matter how good [Mahomes] is, how good the receivers are, how good Kelce is, how good our running backs are. We've seen all these guys and what they can do [when given time].

"You leave the game thinking your unit lost it for the team."

The Chiefs didn't try to alleviate pressure by calling more running plays. They tried runs on just 14 of their 57 plays. LeSean McCoy, their leading rusher entering the game, got no carries.

"They were banged up a little bit in the secondary," Reid said of the Colts. "I thought we could take advantage of that."

The Chiefs weren't productive with the run, gaining 36 yards. A more concerted effort to run the ball might have made a difference.

Lots of man-to-man coverage. This isn't new for the Chiefs, but the Colts did a better job of it than many of Kansas City's other opponents had done.

"Detroit did it last week," Mahomes said of seeing plenty of man coverage. "New England did it in the playoffs. We're going to have to beat man coverage at the end of the day. We've got the guys to do it. Now it's about going out there and executing whenever teams present it to us. ... If we don't, we're going to keep getting it."

Catching the Chiefs at the right time. The Chiefs lost wide receiver Sammy Watkins to a hamstring injury on their first possession of the game. That means they played almost the whole way without either of their starters, as Tyreek Hill hasn't played since Week 1. The Chiefs' leading receiver Sunday was Byron Pringle, who caught six passes for 103 yards and one touchdown. Pringle, a second-year player out of Kansas State, had a previous career high of one catch for 13 yards.

The Chiefs also played without left tackle Eric Fisher, who last month had surgery for a sports hernia. His replacement, Cam Erving, struggled to block Colts defensive end Justin Houston.

The Chiefs have succeeded through offensive injuries before, but the injuries caught up to them against the Colts.

Facing a hobbled Mahomes. He sprained his ankle in the season opener, and though his injury hasn't been discussed much publicly because he has practiced and played, it has been a problem for him. Mahomes has thrown incomplete to more open receivers than he normally would.

The ankle was a bigger problem for Mahomes against the Colts. He aggravated the injury in the first half and again in the third quarter, when he was accidentally stepped on by a teammate. Mahomes at that point was limping noticeably. He was able to finish the game but wasn't as strong as he would have preferred.