Oregon had the best offense in the Pac-12 last year, and there is no question about that by any measure. It wasn't even close. The Ducks averaged nine more points per game than No. 2 California and 1.3 yards more per play than Washington State, Cal and UCLA, while also owning the largest average margin of victory.

In fact, Oregon has produced the conference's best offense every season since 2010. That, in itself, makes it easy to project the Ducks as the conference's best offense in 2015, no matter that Marcus WhatsHisFace is off to the NFL. And ESPN Stats & Information does just this in its latest preseason FPI projections, ranking the Ducks offense No. 1 in the Pac-12 and No. 4 in the nation, which says a lot for a team that is uncertain at quarterback.

It might surprise some, however, that Stats & Info projects UCLA to have the conference's No. 2 and nation's No. 8 offense this fall. The Bruins, who ranked sixth in scoring and tied for second in yards per play in the conference last year, seem likely to use true freshman Josh Rosen at QB, and that lack of experience behind center tends to be worrisome, no matter Rosen's glittering recruiting pedigree.

So what if we mix up the metrics with some cold, hard facts -- such as returning starters, returning skill, returning O-linemen -- and combine it with some good old subjectivity, a.k.a., the eye test.

Here's how we see the Pac-12's best offenses stacking up heading into the 2015 season.

1. Oregon

Returning starters: 7

QB: Eastern Washington transfer Vernon Adams or redshirt junior Jeff Lockie

Returning skill: The Ducks welcome back their top four receivers, led by Byron Marshall, not to mention Bralon Addison, who is returning from a knee injury. They also return their top two running backs, including second-team All-Pac-12 pick Royce Freeman.

Returning O-line: Three starters are returning as well as OT Tyler Johnstone, an All-Conference candidate who sat out last year with a knee injury.

FPI ranking: 4 (No. 1 in Pac-12)

Verdict: Not to diminish the departure of first-team All-Pac-12 offensive linemen Hroniss Grasu and Jake Fisher, both of whom were NFL draft picks, but the only question with the Ducks is QB, and that is a question the program has successfully answered for several years running. There is just so much talent here, though there are several health questions that might prove concerning. Adams, dynamic as an FCS player, even against Pac-12 foes, could be special running this offense, assuming he gets into school. He needs to quickly learn the offense and wins over his teammates. But folks may be selling Lockie short -- even in a competition with Adams.

2. USC

Returning starters: 8

QB: Cody Kessler, a three-year starter and All-American candidate

Returning skill: Kessler, No. 2 RB Justin Davis and No. 2 WR JuJu Smith.

Returning O-line: Five starters, including first-team All-Pac-12 center Max Tuerk, as well as former starting tackle Chad Wheeler, who missed the final five games last year with a knee injury. This should be one of the best O-lines in the nation.

FPI ranking: 14 (No. 3 in Pac-12)

Don't be surprised if Cody Kessler and the Trojans improve upon their 35.8 points per game average last season. Kirby Lee/USA TODAY Sports

Verdict: Just imagine if RB Javorius Allen and WR Nelson Agholor had opted to return instead of entering the NFL draft a year early. As it is, there's not too much concern at the skill positions as the Trojans are plenty capable. Further, Kessler may be the most accurate passer in the Pac-12, and this talented, deep O-line is going to make any RB and QB-WR combination look good. The Trojans averaged 35.8 points per game last year. Don't be surprised if that number perks up to around 40 this fall.

3. California:

Returning starters: 8

QB: Junior Jared Goff, a three-year starter and a likely NFL first-round draft pick next spring

Returning skill: The Bears welcome back their top two running backs, led by 1,000-yard rusher Daniel Lasco, as well as three of their top four receiver, led by Kenny Lawler.

Returning O-line: Three starters.

FPI ranking: 15 (No. 4 in Pac-12)

Verdict: The Bears ranked second in the conference with 38.2 points per game last year and the personnel losses shouldn't have much impact. In fact, every position group should be better this fall than it was last year, which obviously suggests the Bears will score a lot of points. Goff, in particular, appears ready for a breakout performance in year three under Sonny Dykes. He was sacked just 27 times last year, so a more seasoned offensive line should help Goff be more efficient carving up opposing secondaries in Sonny Dykes spread offense.

4. Arizona

Returning starters: 7

QB: Sophomore Anu Solomon is a second-year starter

Returning skill: The Wildcats welcome back Solomon, three of their top four receivers, topped by 1,000-yard receiver Cayleb Jones, and sophomore running back Nick Wilson, who rushed for 1,375 yards and 16 TDs last year.

Returning O-line: 2

FPI ranking: 24 (No. 6 in Pac-12)

Verdict: The offensive line is the biggest issue. Yet while things are uncertain at center and the O-line depth is a question, replacing two OTs is not a worry, as Cal transfer Freddie Tagaloa has NFL talent and Lene Maiava has starting experience. If there is a second issue, it's whether Solomon will take a step forward in terms of consistency after he struggled late last season as the wear and tear on his body seemed to affect his performances. Otherwise, this unit sets up to improve upon the 34.5 points per game it scored last year. Plus, there's the Rich Rodriguez factor. He's the best offensive head coach in the nation. This will be his first Pac-12 experience with a returning starter at QB, and one suspects he will make the most of it.

5. UCLA

Returning starters: 9

QB: True freshman Josh Rosen or junior Jerry Neuheisel

Returning skill: The Bruins will surround whoever wins the QB job with running back Paul Perkins, who led the conference in rushing a year ago, and five of the top-six WRs from 2014, led by Jordan Payton.

Returning O-line: Four starters are back, officially, led by second-team All-Pac-12 center Jake Brendel, but six returning linemen have extensive starting experience.

FPI ranking: 8 (No. 2 in Pac-12)

Verdict: Much like Oregon, the only question here is quarterback, where Rosen is expected to prevail based on pure talent. The difference is the Ducks have more experienced options behind center and, well, averaged two more TDs per game in 2014. While the Bruins offensive line yielded a bunch of sacks last year -- a conference-worst 41 -- many of those fell on Hundley, a fearless guy who often held onto the ball too long. The run blocking certainly showed the Bruins were capable in the trenches -- 4.9 yards per carry, second only to Oregon -- and now this is a veteran group. One suspects that coordinator Noel Mazzone will protect his QB and figure out ways to distribute the ball to his numerous playmakers with minimal risk.

6. Arizona State

Returning starters: 7

QB: Fifth-year senior Mike Bercovici started three games last year and played well.

Returning skill: D.J. Foster is back, and he was a 1,000-yard rusher and the No. 2 WR last year. He's going to be a slot back this fall because the Sun Devils are happy with their talent and depth at running back. Foster is only returning WR with more than 16 receptions.

Returning O-line: 3

FPI ranking: 42 (No. 8 in the Pac-12)

Verdict: While the questions at offensive tackle and receiver are significant, this is one that FPI is getting wrong as the Sun Devils should be potent this fall, perhaps matching last year's 36.9 points per game. Bercovici has one of the best arms in the conference, so count on Mike Norvell, one of the nation's best offensive coordinators, figuring out ways to attack downfield in the passing game. The offensive line's interior boasts perhaps the conference's most physical troika, so expect a smashmouth element with the Sun Devils.