The Denver Broncos are set up for success in 2025. The team hadn't made the postseason once after their Super Bowl 50 win until last season when Bo Nix emerged as the franchise's savior.

While the quarterback was impressive as a rookie, it was still the defense that led the way. Denver's defense led the league with 63 sacks, and they only got better with the additions of Dre Greenlaw, Talanoa Hufanga, and Jahdae Barron. The team now has arguably the best defense in the NFL.

The offense is in good shape, too. Nix has Courtland Sutton, Marvin Mims, and free-agent signee Evan Engram to throw to, and Denver drafted RJ Harvey to take over at running back. The offensive line should be dominant as well. Still, the Broncos don't have a perfect path to contending for the Super Bowl.

They are still somewhat young and unproven, and the dynasty that is the Kansas City Chiefs still plays in their AFC West division. If Nix avoids a sophomore slump and improves to the status of elite, then the Broncos should be in good shape, but they may need a surprise player to help them exceed expectations.

So what player that isn't being talked much about could step up and make a big impact this year?

Ja'Quan McMillian could be the Broncos' X-factor

Kansas City Chiefs tight end Noah Gray (83) runs the ball as Denver Broncos cornerback Ja'Quan McMillian (29) defends in the first quarter at Empower Field at Mile High.
Isaiah J. Downing-USA TODAY Sports

The Broncos' best position group is the cornerback room. Patrick Surtain II is the reigning Defensive Player of the Year, Barron was drafted in the first round of the 2025 NFL Draft, and Riley Moss was exceptional outside of a bad game against the Cincinnati Bengals last season.

The passing defense is boosted by a great pass rush. Nik Bonitto, Jonathan Cooper, and Zach Allen combined for 32.5 sacks last season. If the Broncos can remain at full strength, teams are going to struggle to throw the ball against their starting unit.

Teams are never fully healthy in the NFL, though, and cornerbacks, in particular, often deal with injuries. Some of Denver's worst defensive games last season came when Moss was on the sidelines.

Luckily, the Broncos have the best fourth-option cornerback in the NFL. Ja'Quan McMillian is not a household name, but he is one of the best slot corners in the league. Expectations are sky high for Barron, who is expected to spend some time guarding slots in nickel packages, but teams can't always count on rookies to thrive right away.

Because of that, McMillian may have a bigger role than fans are expecting. With Patrick Mahomes, Justin Herbert, and Geno Smith throwing the football in the Broncos' division, the team will need all of the secondary help that they can get, making McMillian their biggest X-factor.

Other Broncos' X-factors

McMillian isn't the only player who can exceed expectations in Denver this year. As of now, the Broncos list J.K. Dobbins as the starting running back. The rushing attack was arguably the weakest part of Denver's roster last year, which is why they let Javonte Williams walk in free agency.

The Broncos reinforced the backfield with the addition of Dobbins, but he didn't sign until late into free agency for a reason. Dobbins is often injured and potentially past his prime. The draft selection of RJ Harvey is what should really get fans excited.

The Broncos took Harvey in the second round out of UCF. Harvey has speed, power, elusiveness, and balance, and he could become the bell cow back in Denver, especially if injury problems continue to plague Dobbins.

Dre Greenlaw is another X-factor player for the Broncos. At his best during his time with the San Francisco 49ers, Greenlaw was one of the best linebackers in football. However, he tore his Achilles tendon during Super Bowl 58, and he played just two games and nine total tackles last season.

Greenlaw didn't look the same coming back from what is one of the worst injury in sports. However, another offseason of rest and rehab could do him well, and he could return to form as a superstar. If he does, the Broncos got an absolute bargain in free agency. The Broncos have the best defense in football, and Greenlaw makes their ceiling that much higher.