One year ago, UCLA’s offense had a major question mark at quarterback and stability everywhere else. Now, as the Bruins prepare for the start of spring practice, it’s exactly the opposite.

Josh Rosen clearly is the cornerstone, and the Bruins will attempt to rebuild around him. Since last seen on a field, UCLA has lost three starting offensive linemen and four important skill-position players. Plenty of talent remains, but now Rosen must adjust to a new supporting cast and a new offensive scheme.

After an 8-5 season, their worst since 2011, the Bruins won’t remain static when they open spring practice Tuesday on campus. The 15-practice set concludes April23 with the annual spring scrimmage.

Offensive coordinator Noel Mazzone left UCLA for Texas A&M, so the Bruins promoted running backs coach Kennedy Polamalu, a Mater Dei High standout in the 1980s. Polamalu, it seems, will stick with his strength.

Expect the Bruins to embrace a more traditional, run-heavy offense in the spring. Part of that is attributable to personnel, but also the Bruins didn’t hold the ball enough last season. They averaged 25 minutes, 55 seconds in time of possession, and in their five losses, that average dipped to approximately 23:30 when they often lost the battle at the line of scrimmage.

“We need to get bigger, obviously,” UCLA coach Jim Mora said after the bowl loss to Nebraska. “We need to get stronger, obviously.”

UCLA certainly will be comfortable with Rosen, the 2015 freshman phenom who started all 13 games, completed 60 percent of his attempts and passed for 3,670 yards and 23 touchdowns. Rosen had six games in which he threw for at least 300 yards, and NFL scouts already are salivating.

It’s difficult to envision any regression from Rosen, even though he ended last season with some bumps. After a late five-game stretch in which Rosen didn’t throw an interception and UCLA went 4-1, Rosen threw two interceptions against USC and two more against Nebraska as UCLA finished with two losses.

Blips? Probably, but also consider that the Bruins now must replace three starters on the offensive line in addition to 2015 leading rusher Paul Perkins and four of their top five receivers.

Jordan Payton, Thomas Duarte, Perkins and Devin Fuller combined for 185 of UCLA’s 300 receptions last season and 2,478 of the Bruins’ 3,755 receiving yards.

There’s solid depth among UCLA’s receivers, but much of it is untested. Darren Andrews, who finished third on the team last season with 43 receptions and 443 yards (with one touchdown) is the Bruins’ only returning receiver with a significant on-field track record.

The most intriguing spring battle might be the one to replace Perkins, the two-year tailback starter who rushed for 1,343 yards in 2015.

UCLA seemingly has two solid options in sophomore Soso Jamabo and junior Nate Starks, but who is the favorite? Last season, Jamabo ran for 403 yards and four touchdowns while Starks ran for 320 yards and five touchdowns. Starks averaged 6.4 yards per carry while Jamabo averaged 6.1 yards.

The early bet would be on a Jamabo-Starks rotation, unless one of them enjoys a breakout spring, with 220-pound sophomore Bolu Olorunfunmi holding potential as a physical short-yardage back.

All of those skill-position players will require stability from UCLA’s offensive line, which took a hit after the departures of senior center Jake Brendel and juniors Caleb Benenoch and Alex Redmond, who left early for the NFL.

Much of the leadership will fall to senior left tackle Conor McDermott, who passed up a chance to go to the NFL. McDermott, who protects Rosen’s blind side, helped UCLA allow only 14 sacks last season.

Contact the writer: rhammond@ocregister.com