OAKLAND — Raiders cornerback Tarell Brown has been on a good team before. He knows what it takes to win in the NFL.

And after the 41-17 loss Sunday to the Denver Broncos, who ran off five straight touchdowns to put the Raiders out of their misery, Brown was left scratching his head.

“It doesn’t add up,” he said, trying to explain his team and its record. “It doesn’t add up at all.”

You are not alone, Mr. Brown.

This season was supposed to be a bridge to brighter days. Instead, the Raiders have regressed to a point where the Hue Jackson era feels like the glory years. They’re now penicillin for what ails their opponents.

Sure, a .500 season would’ve been an uphill battle. But after $60 million spent in free agency and a successful draft, you’d think they would be competitive. The Raiders are now 0-9, without a win in sight.

How is that possible at this stage of the franchise’s redevelopment?

Sunday was a ringing endorsement for the departure of general manager Reggie McKenzie and every decision-maker underneath owner Mark Davis. Because if the Broncos are the class of the AFC, it was abundantly clear just how far the Raiders have gotten away from even taking the same field as those guys.

The unavoidable truth for this franchise: It’s time to start over. Again. Already.

But the Raiders don’t have much to start over with.

Rookie linebacker Khalil Mack is a keeper. And though Derek Carr has been on a steady decline of late, he’s worthy of building around as the starting quarterback.

Rookie left guard Gabe Jackson is loaded with potential.

After that, who are the Raiders’ keepers? Who are the players you feel good about going forward with?

The Raiders have a few other pretty good players who could be valuable if surrounded by more talent. Linebacker Sio Moore has been productive. Rookie cornerback T.J. Carrie has some skill to work with. Cornerback DJ Hayden is pretty talented for those rare times he is healthy. Offensive linemen Stefen Wisniewski and Austin Howard are solid NFL players. But none of them make you scream playoffs.

Yes, McKenzie gets credit for drafting well the last two years. Several of the bright spots on this team are players he drafted.

He also gets credit for pulling the Raiders out of salary cap hell and setting up the franchise with lots of money for next offseason.

But what good reason is there to trust this regime to use the cap space wisely?

This brain trust had the same opportunity last offseason, and the Raiders still haven’t won a game.

They’re not 3-6 like the St. Louis Rams, who’ve knocked off a couple good teams by sheer grit alone. Not even 2-7 like the Tennessee Titans or 2-8 like the New York Jets, teams that managed to put things together well enough a couple times.

But 0-9. On a crash course for 0-for-2014. Not even the most skeptical of Raiders followers predicted such epic disappointment.

“We gotta stay the course,” interim coach Tony Sparano said. “We gotta believe we’re a better football team.

“I think we’ve got enough professionals in there, enough good young players.”

For 27 minutes, it looked as though Sunday’s game would be the Raiders’ biggest statement that things are at least headed in the right direction. The defense was putting together another impressive outing, even had Peyton Manning looking rattled and nonelite.

The Raiders led 10-6 after Justin Tuck tipped a Manning pass and tracked it down for an interception, which led to a Carr touchdown pass to Brice Butler.

But that inkling of hope for the miracle upset went away quickly as the Raiders morphed back into the Raiders.

The defense, which had found life under Sparano, went back to slapstick tackling. And the Raiders offense was abysmal, managing six first downs and 123 yards before Manning took his seat early in the fourth quarter.

“It comes to a point where you gotta have pride about what you do,” Brown said. “I feel like the guys have pride about coming to work and getting better every day. It’s just that we’re not finishing, we’re not learning from our mistakes. We keep making the same mistakes over and over and over again.”

No play signaled how bad this has gotten more than Carr’s desperate completion to … his left guard. In the eye of a collapsing pocket, Carr dumped it off to Khalif Barnes, who rumbled his way 2 yards before fumbling.

“In my head as soon as I threw it,” Carr said, “I was like, ‘Please knock it down.’ That’s just one of those things.”

The rampant lack of talent and production on display is an indictment on the Raiders decision makers.

Either the Raiders are bad at identifying difference-making players, or they’re bad at developing them. Pick one. The final result is the same: Start completely over.

And there is no way owner Mark Davis can do that with the current decision-makers.

Contact Marcus Thompson II at mthomps2@bayareanewsgroup.com.