With so many new faces playing at important places, Oregon football's expectations appear hazy entering its spring football practices.



But the intrigue surrounding the Ducks -- just three months removed from losing a national title game and four All-Americans to the NFL -- is obvious.



From losing Heisman Trophy winner Marcus Mariota to the NFL to head coach Mark Helfrich gaining both a five-year contract extension and high-profile transfer quarterback, the reigning Pac-12 champions will have considerable amounts of both uncertainty and talent when they meet Tuesday morning for the first of 15 practices.



The formal practices follow two months of winter conditioning workouts that were not overseen by coaches, meaning this is Oregon's first glimpse at how its talented roster could shake out before the brunt of the 2015 recruiting class arrives.



There should be little surprise that quarterback will be the most-monitored position battle of spring after Mariota's departure, but it was the secondary that received a boost of attention Monday with Oregon's announcement that Charles Nelson is moving to the defensive backfield.



It's unknown whether Nelson or the Ducks would entertain the possibility of playing him both ways come fall, as UCLA's Myles Jack and Washington's Shaq Thompson each did in recent seasons.



Nelson spent 2014 as a true freshman Swiss Army knife who made his name on special teams by returning punts and, conversely, razing punt returners before carving out a role at receiver late in the season. Nelson gained 428 yards on 34 touches and scored five touchdowns.

Though switches from one side of the ball to the other remain rare, the need is clear after UO expects to have a deep receiving corps in 2015 while its secondary graduated corners Troy Hill and Ifo Ekpre-Olomu and safety Erick Dargan, each of whom was an All-Pac-12 honoree last season en route to Oregon's school-record 13 victories.



The school also announced that early enrollee and four-star recruit Travis Waller is on campus and ready to contend in the five-man quarterback battle, and will go by his mother's maiden name, Jonsen, on the UO roster.



Jonsen joins a loaded quarterback competition that ranges from him, a freshman who's been on campus only a matter of days, to junior Jeff Lockie, the experienced veteran who served as Mariota's understudy for two seasons. Looming over their spring is the expected June arrival of former Eastern Washington dual-threat quarterback Vernon Adams, who brings three years of starting experience at the FCS level.



Jonsen is the last of six 2015 recruit who graduated early from high school to arrive in time for spring practices, joining receiver Alex Ofodile, defensive lineman Canton Kaumatule, offensive lineman Zack Okun, running back Taj Griffin and corner Ugo Amadi. Jonsen will wear No. 11, the former uniform number of Bralon Addison, who will now wear No. 2.

Addison's story line goes deeper than a number change.

One year after tearing the ACL in his right knee during spring practice, Addison expects to go full-speed for the first time in drills over the course of the next month. Other Ducks whose participation is unknown as they recover from knee injuries include projected starting left tackle Tyler Johnstone, receiver Devon Allen and Griffin. Star defensive lineman DeForest Buckner was on crutches for an unknown leg injury as recently as mid-March.



Other Duck uniform number changes include Allen, who tore his ACL in the Jan. 1 Rose Bowl, wearing No. 13; running back Kani Benoit wearing No. 29; receiver Darren Carrington wearing No. 7; quarterback Ty Griffin wearing No. 10; linebacker Johnny Ragin wearing No. 28; and safety Tyree Robinson switching to No. 3.



You'll have to wait until the spring game, held May 2 at 11 a.m. (Pac-12 Networks), to see Oregon's progress. Practices remain closed.



-- Andrew Greif

agreif@oregonian.com

503-221-8100

@andrewgreif