INDIANAPOLIS --Throughout its 7-0 start, Denver's defense played to the edge -- and then beyond it.
Penalties were a problem, and they cost Broncos some points. But they were usually penalties of aggression, and they didn't cost them any wins.
But when a few other things went wrong against the Colts, they helped bring the Broncos down for the first time this season by a 27-24 margin.
Frank Gore had holes. Receivers streaked open on short and intermediate crossing and out routes. The Broncos attacked and knocked Andrew Luck to the ground 12 times -- including one negated by a penalty -- but only sacked him once.
"We were just out of whack today," said safety T.J. Ward. "We just didn't play Bronco football. "Too many mistakes on defense. We didn't tackle well. It wasn't the scheme that got us. It was assignment errors and penalties."
Penalties. Oh, the penalties.
The validity of the calls will be a subject of ceaseless debate over the next few days. Ward chimed in via Instagram after the game, posting a picture that showed him hitting Indianapolis' T.Y. Hilton with a shoulder-to-chest shot.
But there wasn't much question about how CB Aqib Talib poked Colts TE Dwayne Allen in the eye with two fingers after Allen and Von Miller exchanged words.
"Obviously he's got to keep his composure out there at the end of the game," Head Coach Gary Kubiak said. "The game gets chippy and both sides are talking and you have to handle your business. So that's on me and I've got to make sure that when he's out there, he's got to handle his business."
"We just were Broncos, playing hard at the end of the game. Emotions," Talib added. "You guys ever played football? You ever lost at the end of the game? Remember how that feels? That's how that felt. I was just mad."
Added DE Antonio Smith: "You've got to fight for your brother, man. I've never understood how you can really hang your hat on a rule of saying, 'Second man [in gets penalized],' when you saw the first man ... I guess the second guy is retaliating, so it's out in the open, so you see it."
But whatever the rationalization, that call is going to be made.
That penalty cost the Broncos a chance at a potential game-winning drive, giving the the Colts a crucial first down with 2:25 remaining -- one of seven they picked up via Broncos infractions. And two other penalties gave the Colts first downs on scoring drives that led directly to 10 points.
"We made mistakes," Ward said. "We were just out of sync. It was just one of those games."
Penalties weren't everything; of course, they were the self-inflicted wounds that are, on the surface, easiest to correct.
But will fixing this problem create others if it causes the defense to play with just a smidgen less fury? After all, it's not just execution that vaulted the Broncos defense to the top of league rankings in multiple categories; aggression and intimidation matter, too.
There is a flip side to that, especially in the NFL of 2015, where you sometimes can't hit low and, depending on the situation, you can't hit high, even if the player who incurs the hit drops his helmet, making it impossible for the tackler to adjust.
So can this defense cut its penalties while maintaining its fire?
"We've been working on trying not to get as many penalties, but it's a fine line between playing with your hair on fire and controlling it," Smith said.
"But I'll tell you one thing: Not playing with your hair on fire will get you beat."
And that's what the Colts did early when they jumped on the Broncos, putting them in a 17-0 second-quarter deficit that is their largest of the season to date.
"And we came back out at halftime and we had our hair on fire, and you could see that it was a better style of play," Smith said. "Even though you could see that they were making some plays in the second half, it was a different ballgame."
But something else was different all day: the Broncos' ability to make the game-changing defensive play.
The Broncos hit Luck 12 times. But just one of those hits resulted in a sack. One hit ended in a penalty when Hilton caught a 26-yard pass after going out of bounds. From the rest, Luck went 4-of-10 for 66 yards -- not a great completion percentage, but good for a 6.6-yards-per-attempt average.
Most crucially of all, none of the hits on Luck resulted in a turnover. Indianapolis' gaffe-prone offense protected the football better Sunday than it had all season, and the Broncos didn't force a turnover for the first time this year.
"Late in the game, there were a lot of mistakes, and we didn't capitalize," said Smith.
And then there were third downs. The Broncos came into the game allowing conversions on 31.3 percent of the third downs they faced, but the Colts shredded them on third down, converting 60 percent of their 20 opportunities, with open receivers on underneath routes causing much of the damage.
"Just a terrible showing. We didn't play our game at all," said CB Chris Harris Jr. "Just a bad day. Terrible day."
The Colts' 12 third-down conversions were the most against the Broncos in nearly 13 years. The last team with that many successful third-down attempts? It was, well, the Colts, who converted 15 of 21 third downs through a snowstorm on Nov. 24, 2002, but needed overtime to rack up that total.
As a result of those third downs, the Colts controlled the ball for 38 minutes, 39 seconds -- the most against the Broncos since Week 5 of the 2011 season -- a 29-24 loss to San Diego.
That day also witnessed a comeback that fell short; the Broncos dug themselves a 23-7 hole, then nearly climbed out of it before falling to 1-4. They lost that day, but they won seven of their next eight games.
The scenario is different for these Broncos; they don't need to save their season. Although they trail by one game in the race for the AFC's top seed, they lead the AFC West by three games. Only three teams league-wide have better records, and two of them visit Sports Authority Field at Mile High in the next seven weeks.
There is ample chance for redemption. But the Broncos can't repeat the shortcomings that doomed them to a sixth consecutive loss in Indianapolis.
"We're still the same team. We've still got playmakers," Harris said. "We just can't bring this type of effort next week at all."
The Broncos lose their first matchup to the Colts in Indianapolis.