ENGLEWOOD—Vance Joseph has dared to tweak what wasn’t broken.

As the Broncos’ first-year head coach, Joseph inherited a Denver secondary that was widely considered the NFL’s best, both anecdotally and statistically.

The personality of the Denver defense the previous two years under coordinator Wade Phillips was man-to-man coverage.

Joseph and new defensive coordinator Joe Woods have employed far more zone coverage this season. Hey, it is called the No Fly Zone, not the No Fly Man.

One reason for the mix, Joseph said, is to make it a less physically taxing on cornerbacks Aqib Talib, Chris Harris Jr. and Bradley Roby.

“It’s a physical reason it’s also a scheme reason,’’ Joseph said in a sit-down interview 9News last week. “If you’re all man, you’ll get all man beaters as far as a pass contest. If you’re a mix of man and zone then they’re guessing. So to help our players we thought we have to play more zone. And be good at it.’’

There’s been some growing pains. It’s not that the Broncos have been a sieve against the big pass play – 24 teams have surrendered more pass plays of at least 20 yards than Denver’s 10. It’s that they’ve given up at least one costly big play a game.

There was the 38-yard touchdown to the Chargers’ Travis Benjamin in the opener. A 28-yard touchdown to Dallas tight end Jason Witten in week 2. Four completions of at least 25 yards surrendered in a week 3 loss at Buffalo. And the 64-yard touchdown pass from the Raiders’ Derek Carr to Johnny Holton last week.

“To play more zone coverage you need more focus on details,’’ Joseph said. “This team has been a man-to-man team primarily in the past. That’s an easy job as far as assignments. It’s hard job as far as physical ability. But we want to give our guys a break from time to time and play more zone.

“The issues we’re having now is going to make us a better football team if we can play zone from time to time to give our guys a break. I think the issues we’re having now is, we’re transforming from being a total man team to being a split team, man and zone. That’s been the issue and we’ll get better at it.’’

The Broncos are allowing 25 more passing yards per game this year compared to 2016. But they’re also the No. 1-ranked defense as they’re allowing 80 less rushing yards a game.

The mix has been a 3-1 record.

“Most of the personnel hasn’t changed,’’ Joseph said. “Most of the staff hasn’t changed. Most of the calls haven’t changed. We expected to be a good defense. And we can do better. The first four weeks have been good, but we can do better as far as giving up the big plays.’’