While most Pac-12 teams don't begin spring practices until March, Arizona is set to kick things off Friday. That means we need to quickly refocus from looking back at the 2015 season and celebrating -- or bemoaning -- national signing day and start to examine issues teams face heading into the 2016 campaign.

Here are 10 concerns for you to cogitate over during the coming months.

1. Transfer QBs: Only four conference teams will feature returning starters at quarterback this spring, and with the remaining eight, only five -- some might say three -- have wide-open battles without a clear favorite to win the job. A big reason for that is three transfers who are expected to start in 2016: Dakota Prukop at Oregon, Davis Webb at Colorado (joins team in June while the injured Sefo Liufau potentially redshirts) and Darell Garretson at Oregon State. Some might include former Washington QB Troy Williams at Utah, but he's not as much of a proven, experienced commodity as the others. Of course, you never know -- until you do! -- and somebody might make an unexpected move this spring.

2. Helton takes over at USC: A new coach at USC is always a big deal both regionally and nationally, but Clay Helton was the Trojans' interim coach over the second half of 2015 and was handed the full-time gig before the season ended, so it feels as though we know him fairly well. Still, this is his first spring with his own hand-picked staff and with ultimate decision-making power over personnel and schemes. He did a solid job on signing day, but just about every previous USC coach has also. He's a very different guy than predecessors Lane Kiffin and Steve Sarkisian -- most would say that's a good thing -- and it will be interesting to see how he puts his brand on a talented team that should be in the thick of the Pac-12 race.

3. Returning star power: The Pac-12 will be well-represented on preseason Heisman Trophy watch lists, led by Stanford running back and 2015 runner-up Christian McCaffrey. Also of note are UCLA quarterback Josh Rosen, Oregon running back Royce Freeman, USC receiver JuJu Smith-Schuster, Washington State quarterback Luke Falk and Washington running back Myles Gaskin, among others. Of course, if you aren't getting better, you're getting worse, so these guys need to redouble their efforts on an individual level as well as take more vocal leadership roles on their teams.

4. Getting defensive? Just two members from the front sevens of the first and second All-Pac-12 defensive teams return in 2016. The 2015 NFL draft hit Pac-12 defenses hard, and attrition will be less star-studded but more total this fall. While there's a ton of talent coming back in the secondary, stopping the run was a problem last fall and could be an issue in 2016. If you were going to ask a question that includes just about every Pac-12 team, it would be "How do we get more physical on the defensive front?" And, yeah, that even includes burly Utah, which loses the Pac-12's best inside-linebacker combo in 2015, Gionni Paul and Jared Norris.

5. Wide-open QB battles? Fair to say QB competitions at Arizona State, California, Stanford, USC and Utah are -- to varying degrees -- wide open. That said, allow us to light the fire. The favorites to win starting jobs for those five are Bryce Perkins at Arizona State, Chase Forrest at Cal, Keller Chryst at Stanford, Max Browne at USC and Williams at Utah.

6. New offensive coordinators: Arizona State, California, Oregon, Oregon State, UCLA and USC each have new offensive coordinators. So they'll be getting to know their talent and tweaking things this spring. That said, we expect a pretty high degree of continuity in terms of scheme, though UCLA coach Jim Mora is on record as saying he wants a more physical, less spread-out attack going forward. Oregon, Oregon State, UCLA and USC hired from within, while Arizona State and Cal picked coordinators who ran similar schemes at their previous spots.

7. New defensive coordinators: Arizona, Oregon, Oregon State, USC and Utah each have new defensive coordinators. Unlike the offensive hires, there was a fair degree of importing new schemes here. Arizona brought in Marcel Yates from Boise State after Jeff Casteel was fired, while Oregon hired former Michigan coach Brady Hoke after Don Pellum was demoted. The Ducks will switch to a 4-3 look this spring, while it's uncertain what Yates has in mind for the Wildcats -- he ran a base nickel with the Broncos, which isn't too far off from Casteel's 3-3-5. New Oregon State D-coordinator Kevin Clune has longstanding ties to head coach Gary Andersen, so they'll likely be in accord. USC brought back Clancy Pendergast, who did an outstanding job with his 5-2 during his first tour with the Trojans. When John Pease retired at Utah, he was quickly replaced by Morgan Scalley, who has coached the Utes safeties since 2008.

8. Next step for QB vets? Rosen, Falk, Arizona's Anu Solomon and Washington's Jake Browning are the four returning starters at QB. While Rosen had a strong true freshman campaign, the expectations will be stratospheric for him in 2016: He might be the most talented QB in the nation. Falk will be expected to fine-tune a pretty darn efficient effort from 2015, while Browning should take a step forward from "Don't screw things up" to "He can beat you." Solomon will try to do a rewrite on a disappointing 2015 as a second-year starter.

9. Stanford line of scrimmage: Stanford is one of the nation's premier line-of-scrimmage smashmouth teams. That is where the foundation was laid for the Cardinal's climb into the nation's elite. But Stanford has some questions on both lines heading into spring practices, with just two starters back on the O-line and one on the D-line. The cupboard is not bare by any stretch. The expectation here is that Stanford will again boast top-notch lines. But there's uncertainty at this point, and there could be some growing pains -- see 2014 on the O-line -- as the new starters try to jell. Good chance that one or two of the incoming frosh D-line recruits could play.

10. Who's the riser? Washington State and Cal were the big climbers in the conference in 2015, adding six and three wins, respectively. So what team(s) makes a charge in 2016? More than a few folks see Washington as a potential top-25 outfit that could challenge in the North Division. Is Colorado -- finally! -- ready to step over some folks in the South? It's highly likely that a team not generating much buzz right now will lay the groundwork this spring for a surprising rise in the conference pecking order. Of course, one or a few teams might go in the other direction, but we want to end on a positive note.