Changing of the guard among Pac-12 football powers?

It was a classic Saturday night at Oregon’s home field, Autzen Stadium. The game started slow, then exploded into a rout in the second and third quarters. There was a streak of six unanswered scores, all touchdowns. The victor dominated with more than 500 total yards in a 62-20 thrashing.

So it was just another night in Eugene, Ore. - except it was the Ducks (2-2, 0-1 Pacific-12) on the losing end. Utah (4-0, 1-0) consecrated what looks like its best season since joining the Pac-12 in 2011. The Utes had already beaten Michigan, which defeated Brigham Young on Saturday and was ranked, at No. 22, on Sunday for the first time in the Jim Harbaugh era.

Still, Saturday belonged to Utah, which blew out the conference’s resident power.

“There’s not a ton to be said,” Oregon coach Mark Helfrich said after the game.

The prognosticators who decide the weekly Associated Press poll made clear that, to them, the result did not indicate the Utes’ elite status so much as Oregon’s frailty. Utah moved up to No. 10 from No. 18, whereas Oregon dropped out of the Top 25 from No. 13 (the balloting suggested that voters esteemed them No. 27).

It is tempting to declare the end of an era at Oregon. The Ducks’ current number of losses equals the most they have had over an entire season since 2009. Entering this season with the fourth-most wins of any Football Bowl Subdivision team in the past decade, they are now at .500 and in the midst of their conference schedule. Is the program that played in two national championship games in the past five years fading as quickly as its famed offense runs plays?

The scary thing for Ducks fans is that there is a specific name to which the paranoid may point: Chip Kelly. Although Oregon’s rise can be traced to 20 years ago, when two prominent bowl losses prompted Phil Knight, a founder of Nike, to invest his largess in his alma mater’s football team, the present era of Ducks dominance began with Kelly’s arrival as offensive coordinator in 2007 and reached its apex with his ascension to head coach two years later. This narrative ignores last season, when Kelly was ensconced in his current job as coach of the NFL’s Philadelphia Eagles, and Oregon won the Pac-12, appeared in the national title game and went 13-2. But the man arguably most responsible for last year’s achievements was Heisman Trophy-winning quarterback Marcus Mariota - a Kelly recruit running Kelly’s offense. It was, in other words, Kelly’s final season of major influence at Oregon.

Mariota now starts for the Tennessee Titans, and this offseason Oregon handed the starting duties to a graduate transfer from a Football Championship Subdivision program, Vernon Adams, who had to pass a math test in order to play and who already has been replaced by Jeff Lockie.

Entering this season, some observers feared the Pac-12 would commit what Condoleezza Rice last season termed “fratricide” - that its talented conference members would beat up on one another and in that way prevent one team from standing out.

Rice, the former secretary of state who is a member of the College Football Playoff selection committee, knows something about how hegemony is established. As a Stanford professor, she must have been both heartened and a little miffed that in the end the conference was salvaged by Oregon’s typical dominance.

But her fear could come true, as Saturday contained more friendly fire. Southern California (3-1, 1-1), then ranked No. 19, exposed Arizona State (2-2, 0-1) with a 42-14 victory, a week after falling at home to No. 18 Stanford (3-1, 1-0). (That the Trojans outrank the Cardinal, even though they have the same record and lost head-to-head, is not a typographical error, although it may be one of a different kind on the part of AP voters.) California improved to 4-0 with a 30-24 victory at Washington (2-2, 0-1).

If a changing of the Pac-12 guard happened, it happened in Tucson, Ariz. There, Arizona (3-1, 1-1), which entered the game ranked 16th, was demolished, 56-30, by UCLA (4-0, 1-0), then No. 9. The Bruins were led by quarterback Josh Rosen, who over four games has completed more than 60 percent of his passes, thrown for seven touchdowns against four interceptions and led an offense averaging nearly 38 points per game.

Also Saturday night, he tucked the ball under his shoulder in the red zone and ran it in. “Unbelievable,” offensive coordinator Noel Mazzone called that play, according to UCLA’s student newspaper. It was the first rushing touchdown of Rosen’s season - and of his college career.

While USC is looking for a Heisman-caliber season under center from senior Cody Kessler, Stanford is limiting senior Kevin Hogan because of injury concerns (he threw only 14 passes in a 42-24 victory over Oregon State on Friday) and Oregon is toggling between a senior and a redshirt junior, the Bruins are content with Rosen - who might be the best of the bunch, and he is just a true freshman.