In 2013, the Broncos went to a Super Bowl thanks to Peyton Manning and a record-setting offense.

In 2015, the Broncos won the Super Bowl thanks to Von Miller and a historically great defense.

Here it is 2017 and general manager John Elway is again turning weakness into strength. Last season, the Broncos had two primary problems. One, they couldn’t run the ball. They ranked 27th in the league with a mere 92.8 yards per game.

Two, they couldn’t stop the run. Denver’s defense ranked 28th by allowing an average of 130.3 rushing yards.

Two weeks into the 2017 season, the Broncos have flipped to old-school football. They rank No. 3 in defending the run, allowing just 52.0 rushing yards on average. They are also No. 1 in rushing, averaging 159.0 yards per game. The running game in turn has helped Trevor Siemian become the league’s 5th-most efficient passer (minimum two games played) thanks to his 6 touchdowns against 2 interceptions and 65.0 completion percentage.

What gives with the improved running game? Start with a near overall upfront on the offensive side.

“I think it’s two-fold,’’ said Broncos coach Vance Joseph. “I think it’s personnel driven—offensive line wise, signing (Ron) Leary, who is playing really well right now for us. He was the best guard in free agency in my opinion.

“Signing Menelik Watson, a big-tough-physical guy and drafting (Garett) Bolles. That’s made it different. Matt (Paradis) coming back from his hip injuries and playing well. Max Garcia and trading for Allen Barbre. We’ve fixed the offensive line.

“Now, it hasn’t been perfect, but the run game, it’s there. Our pass protection is not there, yet. We’re still working some kinks out there, but the running game is there. It’s personnel-based and it’s also scheme. Schematically it’s different then what we did last year.’’

The Broncos were a zone-blocking team the previous two years, which is a more athletic, finesse-style of moving defenders. They’ve gone back to a power blocking scheme this year where it’s more of a mauling, one-one-one task.

It also didn’t hurt that running back C.J. Anderson has returned healthy after suffering a season-ending knee injury in game 7 last year. And Anderson has been nicely complemented by veteran Jamaal Charles.

Besides adding Leary, Watson, Bolles and Barbre to the offensive line, Elway also fortified the defensive front by signing veteran nose tackle Domata Peko. And after defensive end Jared Crick went down with a season-ending back injury, second-year, second-round draft pick Adam Gotsis was given a chance to blossom, as was low-priced free agent Shelby Harris. And the team figures to break in free agent Zach Kerr this Sunday at Buffalo after he missed the first two games to recover from a knee injury.

“Schematically, we’re fitting the run game differently,’’ Joseph said. “Our backers are getting downhill faster so the double teams aren’t as tough on our interior D-lineman. It’s both. It’s personnel and it’s scheme.”

Joseph didn’t take credit for changing the team’s mentality. By going full pads for the near-maximum days of practice during training camp and the preseason, and not giving a dozen or so veterans a day off every three days, the Broncos have become more physical during the week and it’s carried into the game.

Eventually, Joseph may have to monitor his players to make sure his big guys don’t wear down as the season goes along.