DENVER -- In the end, it might not have been the exact word Oakland Raiders linebacker Khalil Mack wanted to use, but it was certainly the best one to describe what happened Sunday in Sports Authority Field at Mile High.

“We were able to steal this one,’’ Mack said, “and leave their home with a win.’’

And with that, the Broncos’ joyride with backup quarterback Brock Osweiler -- three wins in the 25-year-old’s first three career starts -- hit a rather significant bump in the road in an ugly 15-12 loss to the Raiders.

Brock Osweiler and the Broncos managed just 6 yards of offense in the third quarter on Sunday. AP Photo/Joe Mahoney

The Broncos' offense didn’t score a touchdown, dropping passes at the worst times -- especially Demaryius Thomas and Vernon Davis -- and rushing for only 34 yards. Osweiler was also sacked five times, all by Mack.

Broncos coach Gary Kubiak summed it up: "We had many, many chances to get it done and we didn’t get it done.’’

There were times Sunday, like in Osweiler’s previous starts, when he looked like a guy just getting going on the learning curve of being an NFL quarterback. Times when he held the ball too long, missed a throw with the game in the balance and had passes batted down at the line of scrimmage. And there was the safety.

With just under two minutes remaining in the third quarter, the Broncos faced a third-and-9 at their own 3-yard line. The Broncos led by five at the time, so they were trying for the first down, but a punt wouldn’t have been a horrible outcome. Osweiler thought he had a receiver open and tried to get the ball away as Mack hit him.

The result was a fumble; Broncos guard Max Garcia fell on it in the end zone. The Raiders got the safety, cut the Broncos' lead to 12-9, and the momentum that had been the Broncos’ in the first half had officially been packed up and moved to the Raiders' sideline.

In all, the Broncos’ offensive output in the third quarter was four three-and-outs, 6 total yards, a Thomas fumble and the safety.

“I felt the pressure, I knew it was coming,’’ Osweiler said. “Obviously, I knew that he would be coming quick. Unfortunately, there was a situation where I had an open receiver. I was trying to get the ball out. ... He got there faster than I could get the football out.’’

Osweiler has been sacked 17 times in just over 17 quarters played. That’s far too many for a team that is perilously close to wasting the greatest defensive season the franchise has seen and still considers itself in the Super Bowl chase.

Kubiak said, "We lost the line of scrimmage … we didn't move them around, in my opinion … it was obvious the line of scrimmage was won by them.’’

And Mack’s perspective on his first five-sack game of his career?

"[Osweiler] held the ball a lot longer than Peyton [Manning] did,’’ Mack said.

It is unfair to judge Osweiler against future Hall of Famer Manning. But playing quarterback in the NFL is to be judged on a minute-by-minute basis. While Osweiler has been composed, confident and shown he has the makings of a starter, defenses have gone to school on him in four weeks and the Broncos' offensive line hasn't proven it can protect him.

The Broncos' defense, on the other hand, is No. 1 in scoring defense, total defense, sacks and pass defense. It held the Raiders to minus-12 yards in the first half. Oakland didn’t have 100 yards of total offense until the opening minute of the fourth quarter, and the Broncos held the Raiders’ top two receivers -- Amari Cooper and Michael Crabtree -- to a combined four catches for 19 yards.

The Raiders' winning touchdown drive went for all of 11 yards after Emmanuel Sanders muffed a punt.

So, the Broncos lost. Let one get away because of their special teams -- a muffed punt and missed field goal. And now, while the narrative for some is Manning returning to save the season, he just started throwing and hasn’t practiced with the team in a month. His return is still a significant question mark.

If the Broncos are going to stay in the hunt for home-field advantage in the AFC and earn a coveted playoff bye, Osweiler has some heavy lifting to do. And the rest of the Broncos’ offense just needs to step up and help the kid out.