EUGENE -- We continue our review of Oregon Ducks spring football, position-by-position, and attempt to project what UO could look like when fall camp rolls around in August.

The questions we will try to answer for each position include, what did we learn? What questions still remain? What new questions popped up? Two weeks ago we finished the reviews of the defense and special teams. Now we get into the offense.

Today, the running backs.

Judging by social media this spring, the running back position seems to inspire three types of Duck fans: Those who have Byron Marshall's back, those who have Thomas Tyner's, and those who believe in incoming freshman Royce Freeman.

So here's a friendly reminder that the answer can be multiple choice come fall, just as it was a season ago when Marshall, Tyner, Marcus Mariota and De'Anthony Thomas ran for 273.5 yards per game and 6.3 yards per rush.

Whether Oregon uses Marshall, the junior, or Tyner, the sophomore, as a runner or receiver each has the skills and speed to change a game. Their crossover and complimentary skills -- Tyner is the speed back, while Marshall grinds out yards between tackles -- could mean Oregon might have another two-headed backfield on its hands. Marshall and Tyner have the potential to join Maurice Morris/Onterrio Smith of 2001 and Jeremiah Johnson and LeGarrette Blount of 2008 as Oregon duos who each rushed for 1,000 yards in the same season.

We knew about their versatility last fall, of course, after Marshall's breakout 1,038-yard season and Tyner overcame injuries and questions of maturity for a strong final third of the year. But what we learned in the spring that Tyner has "learned how to practice," coach Mark Helfrich said, and in doing so has become better at investing extra time into the sport.

That showed in the spring game on May 3, when Tyner gained 58 yards on 10 carries. He also had the play of the day when he opted to run over JUCO transfer corner Dominique Harrison instead of a juke for a 19-yard gain. His praise wasn't limited to only the spring game. In early April, offensive coordinator Scott Frost noted: "I'm really impressed with Thomas this spring. If he keeps practicing like he is this spring we're going to have a really good player on our hands. I think he's kind of decided to take it to the next level and it's showing up."

Each compliment of Tyner carries a quiet caveat, though. For Helfrich, it was that Tyner needed to be in better shape when he arrived for fall camp. For Frost, it was "if he keeps practicing like this." By many accounts he had an impressive spring, but following through on the work is just as important. The carrot remains placed firmly in front of the young back.

Marshall had a somewhat quieter spring, though maybe he likes it that way. Marshall plays best when he senses disrespect, and much of the noise exiting spring is on Tyner or the promise of Freeman, the five-star running back who arrives this summer. Marshall's spring game with four rushes for zero yards, a fumble (he recovered it) and 11 receiving yards won't draw headlines, but it shouldn't take away that he has the best receiving hands out of the backfield and is a proven commodity in the Pac-12 crucible.

What we won't know until August is the role of incoming backs Freeman or Tony James, who is recovering from a leg injury in January. Running backs coach Gary Campbell said each will have a shot to play, but taking reps from the improved duo of Tyner and Marshall appears difficult.

Previously:

-- Andrew Greif | @andrewgreif