ENGLEWOOD, Colo. -- Champ Bailey called it.

Eight years ago, the cornerback and Pro Football Hall of Fame candidate had seen an undrafted rookie -- a guy who wasn’t invited to the scouting combine and got the last contract the Denver Broncos had to offer to an undrafted player -- work through a few hours of training camp and pronounced he was “going to be here a long, long time.”

That rookie, Chris Harris Jr., is 29 now. He has been named to three Pro Bowls, he has been a first-team All Pro and he has a Super Bowl ring.

Chris Harris Jr. has shown he can play on the slot and outside. Isaiah J. Downing/USA TODAY Sports

And he might still be one of the most difficult players for any team to acquire. In fact, there are personnel executives in the NFL who, after putting franchise quarterback in Sharpie at the top of the hard-to-find list, would say a cornerback who can do what Harris does week to week might be next in line.

With all of the restrictions on defensive backs and the pass-heavy offenses and the accurate passers, this might is one of the most difficult eras to succeed in coverage.

Harris has flourished, playing at an elite level on the outside and covering many of the league’s fastest receivers in open spaces, but also in the slot. Harris is at his most proficient working in high-traffic areas in the middle of the field.

It's simple to say, but in reality, vastly different skill sets are always difficult to find in one player.

“A guy who can play both positions is just really, really rare, there's no other way to say it," said Broncos coach Vance Joseph, a former longtime defensive backs coach in the league. “To be an outside corner, having long speed, movement, ball skills and quickness, and to be an inside corner, you need those same skills but linebackers’ eyes with the toughness to tackle in the box, play leverage, blitz, all those things.”

It also puts the Broncos, who have finished first, first and fourth in the league in pass defense over the previous three seasons, in the position of trying to decide the best way to use Harris to maximize results. So far, the results haven't been what they want. Russell Wilson, Derek Carr and Joe Flacco have completed a combined 69.5 percent of their passes in the Broncos' first three games of the season with a passer rating of 102.2. And now the Broncos are set to face the Kansas City Chiefs at home on Monday night. Quarterback Patrick Mahomes and the Chiefs are averaging nearly 300 passing yards per game.

Bradley Roby is still working into his new job description as an every-down cornerback who has taken Aqib Talib's old job in the defense. The Broncos added two cornerbacks in free agency -- Tramaine Brock and Adam Jones -- to play one of the outside spots when needed in the specialty packages, but both of those players already have battled injuries.

The dilemma is Harris is the team’s best cornerback outside and also the best in the slot, but he can only play one of those spots at a time. So, part of an opponent's planning has been to use formations and personnel groupings at times to try to limit Harris’ ability to affect a play.

“I’ve always just tried to be as good at everything as I could be,” Harris said. “... Some games they don’t throw at me at all, but my job is be ready all the time to make a play no matter where I am.”

The Chiefs lead the league in scoring, at 39.3 points per game, and Kansas City coach Andy Reid employs a wide array of impact players in a motion-filled assortment of formations. In short, getting Harris in the best spots to do his best work is part of what the Broncos will try to do this week. But Harris also represents a luxury most defenses don’t have.

“I don’t think there are many, maybe not any, guys like Chris,” Broncos linebacker Von Miller said. “Especially now, when everybody, it seems like, has receivers and tight ends who all run fast and catch the ball.”

So Harris has to be fast with the fastest and physical with the strongest. And he has to handle calls in the secondary.

“Chris isn’t as big as some corners, but he can play outside because he’s got great, great, great quickness and he’s aggressive and he can always find the ball,” Joseph said. “You watch Chris against big guys, he has great timing, great feel for the play; even with the back-shoulder throws, he finds the ball. And in the slot, everything happens so fast and the guy has a three-way go on every play -- inside, outside or go vertical -- so you have to know the offensive concepts to even play in there and also be smart enough to fit in the run game.

"It’s part linebacker, part corner, part safety with a tremendous football IQ; that’s really, really hard to find a guy like that.”