ENGLEWOOD, Colo. -- Throughout the offseason and even into the first weeks of training camp, Denver Broncos offensive coordinator Adam Gase has talked about how "guys would sort out" the depth chart at running back behind Montee Ball.
Well, now the Broncos' youthful corps of backs gets a chance with Ball briefly on the sideline. Ball was undergoing an appendectomy Monday afternoon and is expected to miss at least the Broncos' first two preseason games -- Thursday against the Seattle Seahawks and Aug. 17 at the San Francisco 49ers. He may not even be ready for the team's third preseason game Aug. 23 against the Houston Texans.
The regulars don't play in the fourth preseason game, so even if doctors use a laparoscope for the procedure -- the incision is smaller and there is less damage to the tissue in the surrounding area than in a traditional surgery -- Ball could be held out of all of the preseason games.
He was slated to have a laparoscopic surgery, unless there was some unforeseen issue, and that would mean Ball would have to avoid strenuous activity for up to five days. A more traditional operation would mean Ball would have to avoid strenuous activity for 10 to 14 days before he could begin his rehab.
This gives the team's running backs an opportunity to show what they can do.
"Montee's going to be back ... but it's a big opportunity for all of us," said C.J. Anderson. "You just pushing and keep your head down and grinding and keep doing what you do. If you keep pushing the right way, the coaches will see it."
Ronnie Hillman, who has worked as Ball's backup in training camp, will likely start Thursday night against the Seahawks. Hillman and Ball have been practicing with the starters in all of the drills and walk-throughs so far.
After losing the starting job a year ago and struggling to regain his momentum in the weeks that followed -- a game-day inactive five times in the regular season and for all three of the Broncos' playoff games -- Hillman has been what running backs coach Eric Studesville called "a totally different guy" this time around.
Hillman has shown the explosiveness the team wanted when it made him a third-round pick in the 2012 draft, including an afterburner-worthy inside run during team drills Monday. In a year when the Broncos have turned over the position group, the 22-year-old Hillman, who is entering his third season, is now the most experienced running back on the roster.
"You've just got to take advantage of it," Hillman said. "Just come out here and try not to think about that stuff. Just come out here and do what you can and just try to be accountable for the reps that you do get.”
Anderson, who has worked with the second-team offense much of the time, will work with the starters some in practice in the coming weeks. But the real opportunity may come for a group of youngsters who will have the opportunity to get a little more work now.
Undrafted rookie Juwan Thompson has been the No. 4 back lately. The 225-pounder is the biggest back on the roster. He has shown good instincts in pass protection and been consistent catching the ball. Thompson was a special-teams captain at Duke, so the Broncos are optimistic he can contribute there as well.
Kapri Bibbs and Brennan Clay, both undrafted rookies, each got work in Saturday's scrimmage with the third-team offense. Both will have to show a little more in pieces of the game when they are running the ball -- pass protection, receiving -- to nudge their way past Thompson. A player like Jerodis Williams, who has found practice carries hard to come by, may have some additional opportunities to show what he can offer.
"No mistakes and do the job," Anderson said. "That's what [the coaches] are looking for."