The last time a team other than Oregon or Stanford won the Pacific conference championship, Mark Sanchez was leading Pete Carroll’s penultimate USC squad to Pac-10 — yes, 10 — glory, and Chip Kelly was still an innovative offensive coordinator waiting to take over the program in Eugene.

Except Oregon won’t even reach a bowl game this year, and Stanford’s midseason swoon has removed the Cardinals from Pac-12 contention. This season will bring a new winner. And in that spirit of novelty, it’s fitting that the next Pac-12 champ could be a team that wasn’t even in the conference the last time a different team won — and a team that had five conference wins, total, in its first five years in the Pac-12.

No. 10 Colorado (8–2 overall) has already surpassed that combined total with six conference wins this season. The Buffaloes haven’t played in a major bowl since 2001 and suffered double-digit losses as recently as 2014. But thanks to a resurgent defense, they sit atop the Pac-12 South and, with wins in their remaining games against Washington State and Utah, would play for the conference crown next month.

Such a quick turnaround is nothing new for head coach Mike MacIntyre, who, prior to taking the job in Boulder, transformed San Jose State from a 1–12 team to an 11–2 bowl winner in just two seasons. MacIntyre has a defensive pedigree: He previously served as Duke’s defensive coordinator, winning FBS Assistant Coach of the Year honors in 2009, and as a defensive backs coach in the NFL for five seasons.

Just like the team’s record, the defense has improved swiftly and suddenly under MacIntyre and defensive coordinator Jim Leavitt. Colorado this year ranks tied for ninth in points allowed per game, 12th in yards allowed per game, and ninth in the advanced metric defensive S&P+, which measures a team’s efficiency on a play-by-play basis. As recently as two seasons ago, the Buffaloes defense finished outside the top 100 nationally in all three categories.

The shift started with the secondary, generating a story line that meshes with MacIntyre’s background. Cornerback Chidobe Awuzie was only a two-star recruit out of high school, but the San Jose native came to Colorado after MacIntyre, who had recruited him while in his previous role, joined the program. He blossomed in Boulder, receiving second-team All-Pac-12 accolades and serving as a lone bright spot for the defense last year, his first under Leavitt.

This year, his teammates have joined him in a pact of stinginess. Only Ohio State allows fewer yards per pass attempt, and only OSU, Florida, and Michigan have held opposing QBs to a lower passer rating. On an individual level, fellow corner Ahkello Witherspoon and safety Tedric Thompson lead the Pac-12 in passes defended, and Awuzie falls further down that list only because quarterbacks tend to keep the ball away from the all-conference honoree.

Related Chaos Steps into the College Football Playoff Picture

Picking on the likes of Witherspoon instead hasn’t been a lucrative option for quarterbacks, either. The senior corner has allowed completions on fewer than a third of the passes targeting him, per Pro Football Focus. Thompson, meanwhile, is tied for the Pac-12 lead with four interceptions and has allowed an opposing passer rating of just 34.5 on targets against him, per PFF (using the NFL QB rating formula). The trio has allowed just one touchdown, total, all season.

The secondary is physical and athletic, and its members use their size to outman the Pac-12’s flock of talented receivers. The starting members of the secondary are all at least 6 feet tall and 195 pounds. Witherspoon’s lone interception this year saved an early-season win against Oregon and came as a result of him using his 6-foot-3 frame to win a jump ball in the end zone.

Having the athleticism to close on the ball, as Thompson does here in the Buffs’ ugly 10–5 victory over Stanford last month, helps, too.

The Buffaloes’ dominant pass defense has continued to improve as the season has progressed. In its past four games, Colorado’s opponents have completed just 47.1 percent of their passes for 5.5 yards per attempt. For comparison, Rutgers — the second-worst passing team in FBS — has marks of 47.3 percent and 5.1 yards, respectively, for the whole season. None of the Buffs’ opponents has reached even 200 yards passing in that span; none has thrown for more touchdowns than interceptions.

And while Colorado hasn’t faced a particularly imposing lineup of passing offenses this year, it has still held its opponents far below their usual outputs. (This chart doesn’t include the defense holding FCS opponent Idaho State to just 61 yards on 41 pass attempts.)

Even when it has allowed bushels of points, Colorado’s defense has been solid at the back. Michigan beat the Buffs 45–28 in a surprisingly close September contest, but much of that damage came on the ground: Wolverines quarterback Wilton Speight managed just a 53 percent completion rate and one touchdown pass in the game.

The secondary isn’t alone in its contributions to Colorado’s record, but its partner units have veered more toward mediocrity than excellence. The run defense slots in the 20–40 range nationally, depending on the statistic, rather than the top of the leaderboard, and the pass rush is in a similar range when adjusted by opponent. The Buffs also average fewer than five tackles for loss each game, placing the defense in a tie for 105th in the country.

One way to disentangle the relative contributions of the front seven and the secondary is by comparing the units’ havoc rates, which measure how often a defense has a tackle for loss, pass broken up or intercepted, or forced fumble. A defense like Michigan’s, for instance, fares well by both its front seven havoc rate and its secondary havoc rate, but for Colorado, a dominant secondary (sixth nationally) makes up for an average front seven (61st) in this regard. Those divergent rankings reinforce the collective wisdom around Colorado’s defensive success.

The offense, too, is more of a middling group than a top-tier one. Quarterbacks Sefo Liufau and Steven Montez have combined for 19 touchdowns to just seven interceptions — better than last year, when Colorado’s passers managed just a 13:12 ratio — but overall, the offense is a portrait of mediocrity: seventh in the Pac-12 in passing yards, fifth in rushing yards, and fifth in points per game.

For Colorado, though, even average is an improvement over recent years, and the existence of one elite unit has allowed MacIntyre’s group to fast-forward through the middle stages of a typical rebuilding plan. Colorado hasn’t even reached a bowl game since 2007, yet this year, it’s just a couple of games away from a Rose Bowl berth — even if the Buffs lose in the conference title game, Washington could qualify for the College Football Playoff, which would leave Pasadena desperate to find a Pac-12 team to take a spot in the New Year’s bowl.

To reach that point, Colorado has to defeat ranked opponents in consecutive weeks. The first test is this weekend against Washington State, in a matchup of strengths: Mike Leach’s Cougars, winners of eight straight, boast the second-most-prolific passing offense in the country (386 yards per game). Wazzu quarterback Luke Falk has 17 touchdowns to just one interception over the past month, and his offense’s Air Raid formations and tempo will provide Colorado’s secondary with its greatest test thus far.

Related Penn State Football Is Back

But for the first time in years, Colorado is suited in both personnel and planning to confront that challenge. It brings to mind a story Leavitt told The Denver Post recently, about his recruitment to Boulder, when his wife made the strongest case for the move: “I told her, ‘Well, their defense isn’t real strong.’ She said, ‘That’s your problem.’”

Colorado has to slow a Leach offense, then a solid Utah team, then possibly a playoff contender in Washington in the Pac-12 title game. It’s a problem for MacIntyre and Leavitt, sure. But Colorado is once again playing games with national import in late November, so it’s a good problem to have.