Pac-12 spring practices end on Saturday with spring games from Oregon and Oregon State, and many conference teams feel like they found answers to some of their nagging questions. But there also are major unresolved issues.

So which is the most pressing post-spring void?

Start at Arizona. While the Wildcats QB competition is far from resolved -- heck, four guys are still in the hunt -- the general feeling after spring practices ended is that the position is far better off than it was a year ago. Based on the quality of competition, there's not much concern that the next QB won't be at least solid.

Things now seem more uncertain at running back, where the Wildcats are replacing Ka'Deem Carey. The only returning RB with experience, Jared Baker, was out with an injury. The NCAA waylaid early-enrollee Jonathan Haden, and redshirt freshmen Pierre Cormier and Zach Green didn't distinguish themselves. Senior Terris Jones-Grigsby made a few plays, and incoming freshman Nick Wilson arrives in the fall. It's possible Rich Rodriguez will reach into his deep bag of receivers for help at the position.

The Wildcats running game should be productive because that's pretty much a given with a Rich Rodriguez offense. How productive, however, might determine where Arizona ultimately falls in the South Division pecking order.

Then there's Oregon State, which is only replacing the nation's best receiver in 2013, Brandin Cooks, a potential first-round NFL draft pick next week. The Beavers welcome back the experienced Richard Mullaney and the promising Victor Bolden, but asking them to replace Cooks' production and explosiveness seems far-fetched. With a strong-armed, veteran QB in Sean Mannion, the Beavers need to find more weapons in the passing game.

Meanwhile, UCLA exits spring practices with few obvious voids. There's a reason folks are projecting a top-10 preseason ranking. Yet OLB Anthony Barr was special. He's also a potential first-round NFL draft pick, and the Bruins don't have an obvious answer for replacing his 10 sacks. Kenny Orjioke flashed some this spring, and he and Deon Hollins seem to be a serviceable tandem, particularly if end Owamagbe Odighizuwa becomes a QB terror.

Still, Barr not only was everywhere last year, he made everyone around him better.

Often it's not just about physical skill, though Stanford LB Shayne Skov has plenty of that. Skov was more than the Cardinal's leading tackler. He was the locker room's emotional presence, its unquestioned leader. So it's not just that Stanford is replacing his production. It's also the leadership void he leaves behind.

At the end of spring, it was unclear who would take his place, as Blake Martinez, Noor Davis, Joe Hemschoot and Kevin Palma all are still in the mix.

Finally, Washington is replacing RB Bishop Sankey, its unquestioned offensive superstar, but the QB situation, where the efficient Keith Price needs to be replaced, seems more worrisome. The good news is Cyler Miles wasn't charged in an off-field incident that had him suspended all of spring. That would appear to clear the way for him rejoining the team.

Still, he might be in new coach Chris Petersen's doghouse, and he might not find it easy to catch up with Jeff Lindquist and Troy Williams in terms of learning the new offense. Further, neither Lindquist nor Williams seemed to make a decisive statement this spring. While the options to replace Sankey at RB -- unlike at Arizona -- have quality game experience, that only can be said for Miles at QB. Until Petersen reveals Miles' standing, this is a major question for the Huskies offseason and fall camp.

Each of these teams has high aspirations for 2014. It's unlikely they will meet those expectations without adequately addressing these voids.

So which is the biggest?