"They've been doing a good job," Hagan said. "I'm satisfied with the work Hugh Charles has gotten, Demetrius Sumler has gotten, Byron Ellis has gotten. I'm pretty happy. I think we've improved at that position."
Hagan said his plan as of now is to rotate all three backs this year. The back with the hot hand will stay. While Charles and Ellis were part of last year's rotation of tailbacks — Charles produced 779 yards, Ellis added 126 on the ground — Sumler sat the bench on game days in 2006, taking a redshirt season.
Sumler struggled some during the spring, leading coaches to hope it was a matter of youth. It's looking like Sumler has grown up a bit since then — now the 5-10, 215-pound Sumler is right in the thick of the CU offense.
"He's playing fast," Hagan said. "He's doing all the things we recruited him to do. He adds another dimension to our backfield, with his size and his vision. He's pretty special."
Both Hagan and offensive run game coordinator Jeff Grimes have been working with the tailbacks on the vision part of their games this camp. They want the runners to understand, not just where the hole is supposed to appear when they hit the line, but what each of their blockers are supposed to be doing. Sumler said it's starting to click.
"Instead of telling us where the play is supposed to hit, they explained to us where linemen are lined up and who they're trying to get," Sumler said. "When you understand that kind of thing, it's easier to be patient and set up your blocks.
"Every play is some kind of scheme. I'm able to kind of see where everything is going and try and make a good decision on where I should cut."
Sumler was a workhorse for Cathedral Catholic High in San Diego as a prepster. He finished his career their as the area's all-time leading rusher, with 5,696 yards. The area has produced some great tailbacks, including Marcus Allen, Reggie Bush, Terrell Davis and Rashaan Salaam.
Spending a year with a redshirt on his back has seemed to light a fire under Sumler, who admits he didn't know what he was doing when he got to Boulder a year ago.
"I didn't know how to work this hard every day. I didn't know how to go 100 percent every snap," he said. "(Now), I'm so hungry. I haven't played football (in a game) in a year. That's what wakes me up every morning."
Sumler's emergence has been good for Charles and Ellis, too, according to Hagan.
"That's one thing we've stressed — competition making us better. He's made Hugh better and he's made Byron better," Hagan said.
While Hagan spoke glowingly of Sumler on Saturday, don't expect the coach to offer that kind of flowery speech to Sumler himself. Hagan's about tough love.
Told of what his coach had said about him, Sumler smiled like a hungry man who just had a plate of ribs set down in front of him.
"That's good to hear," Sumler said.