ENGLEWOOD, Colo. -- Age might be just a number, but it can be an important one when facing the Denver Broncos' defense.

Denver's defense, which has finished among the league’s top four in either scoring defense or total defense in four of the past five seasons, has made the Broncos a tough out. And they've been an even tougher out for young opposing quarterbacks.

Older QBs, however, have fared better. Since the start of the 2013 season, the Broncos have lost 18 regular-season games. In 11 of those losses, the quarterback for the opposing team was at least 30 years old.

Of last season’s seven losses, five came to teams with 30-something starters at QB: Alex Smith (twice), Philip Rivers, Matt Ryan and Tom Brady.

Certainly, you'd expect quarterbacks who are still starting games at age 30 and beyond to be more proficient than their younger peers. They've been among the league's best in many cases, but their success is also a testament to the patience and boldness that have been required to outscore the Peyton Manning-led Broncos or to outlast the post-Manning Broncos.

"I think those experienced guys are tougher because they’ve seen more, they’re harder to fool, you have to win more straight-up one-on-one matchups," Broncos cornerback Chris Harris Jr. said. "And you have to be ready because the really great quarterbacks can still come after you late in the game. You can’t ever let up because they won’t."

This season, the Broncos are off to a 2-0 start and sit at No. 4 in total defense. They opened the season by defeating the Chargers, who had 35-year-old Rivers behind center. But Rivers also capitalized on two Broncos turnovers in the fourth quarter to lead two TD drives that closed a 24-7 Broncos lead to 24-21 before the Broncos blocked a Chargers field goal attempt in the final seconds to preserve the win.

The Broncos then manhandled 24-year-old QB Dak Prescott in Denver’s 42-17 win over the Cowboys this past Sunday. It was just Prescott’s 18th career start and the first time he had faced the Broncos’ defense.

Since the beginning of the 2016 season, teams led by quarterbacks in their 20s -- including this past Sunday -- are 2-8 with four touchdown passes and nine interceptions combined in games against the Broncos' defense.

The Broncos go to Buffalo this weekend and 28-year-old Tyrod Taylor will get his first chance at Denver’s defense. The Raiders' 26-year-old Derek Carr, who has been behind center for two wins over the Broncos in the previous two seasons, would be next on Denver's schedule, followed by Eli Manning (36), Rivers and Smith (33) before October closes out.

Brady (40) awaits in November, just after the Broncos get their first crack at Eagles second-year starter Carson Wentz (24) to open the month.

"Those experienced guys, they’ve seen it, done it," Broncos cornerback Aqib Talib said. "Sometimes those young guys play with that freedom, though, too. They don’t worry, they just play, at least the really good ones. But overall, those guys who know what they’re looking at are always going to be tougher."