Collectively, the Broncos' running backs averaged 4.38 yards per carry and averaged one first down every 4.26 carries last year -- a reasonable amount above the league averages of 4.16 yards per carry and one first down every 4.62 run plays.

But C.J. Anderson's explosion into a Pro Bowler in the second half of the season is what brought the Broncos' running game up to where they hoped it would be. A ground game that ranked 27th in the league in yardage per game and 26th in yardage per carry in Weeks 1-11 soared to sixth and 11th, respectively, in Weeks 12-17.

The re-emphasis on the ground game helped stabilize the offensive line, but benefitted Anderson most of all. When the Broncos opened their Week 12 win over Miami with four consecutive run plays, Anderson had all the carries, starting while Ronnie Hillman and Montee Ball sat out with foot and groin injuries that would cost them a combined 17 games. That quick start set Anderson on course for 167 yards in his second start, and the Broncos were off and running in a way unseen since 2011.

With a return to zone blocking in 2015 under Head Coach Gary Kubiak and Offensive Coordinator Rick Dennison, Anderson's rampage through opposing defenses could be just the beginning. Kubiak and Dennison's penchant for extracting career seasons from running backs continued last year in Baltimore, when they helped craft an offense that turned Justin Forsett loose.

"I just can't wait to get to work, to be honest," Anderson said.

But first, let's take a look back.

**

C.J. ANDERSON** Games played/started:15/7
Snaps:495
Contract:Expires after 2015 season

All that separated Anderson from a 1,000-yard campaign was his place on the depth chart during the first half of the season. In Week 5 against Arizona, he was a healthy scratch from the game-day active lineup.

By the end of the season, he was one of the most crucial components to the Broncos' more ground-intensive offense, handling the bulk of the work, with relief from Juwan Thompson, Jeremy Stewart and, finally, Hillman. In Weeks 10-17, Hillman averaged more yards from scrimmage per game in Weeks 10-17 than all but one other running back (Pittsburgh's Le'Veon Bell). That earned him a Pro Bowl selection as an alternate.

Not bad for an undrafted prospect who the Broncos nabbed for a $12,500 signing bonus in 2013.

**

RONNIE HILLMAN** Games played/started:8/4
Snaps:310
Contract:Expires after 2015 season

Hillman's third season saw another new jersey number (23, after wearing 34 and 21 in 2012 and 2013, respectively), the first 100-yard games of his career (Week 6 at the Jets and Week 8 against the Chargers), but, ultimately, a foot injury that cost him six games before he returned to the lineup in Week 17.

It was against San Diego that Hillman finally showed the potential that was only evident in flashes. His 100-yard performance against the Jets was a result of a defense that overplayed the pass and conceded the run; in averaging 5.45 yards per carry against the Chargers, Hillman earned it. He finished the season with 3.99 yards per carry, but only played two games -- the regular-season finale and the playoff loss to Indianapolis -- after the Broncos recommitted to the run.

Time is running out for Hillman to make an imprint on the Broncos. His contract expires after the year, and his long-term viability as an NFL runner could rest on what he does in 2015 and whether he can apply the lessons of a bumpy three years.

**

MONTEE BALL** Games played/started:5/3
Snaps:191
Contract:Expires after 2016 season

After succumbing to a groin strain in Week 5 against Arizona, Ball would later admit that he'd dealt with discomfort in the muscle since Week 1.

"It's me growing up and teaching myself how to be a pro," Ball said in November. "I wasn't telling anybody, so I was just trying to work through it on my own.

"For any rookies that are coming in, make sure that you always tell them (team medical personnel) if you've got bumps and bruises."

His disappointing output in the three and a half games he played to start the season must be viewed in light of playing hurt through almost all of them -- and recovering from an emergency appendectomy just to be ready for the regular-season opener. An aggravation of the injury ended his season in a Week 11 loss at St. Louis, but by the time the Broncos placed him on injured reserve, Anderson had seized the starting job that was once Ball's.

A return to health should help Ball, and zone blocking should create more holes, as well. But with Anderson staking his claim to the top spot and Hillman still in the mix, Ball might have to fight for every opportunity.

**

JUWAN THOMPSON** Games played/started:15/0
Snaps:123
Contract:Expires after 2016 season

After a promising rookie year that ended with multiple nagging injuries, Thompson could be the most intriguing back of the offseason. If the Broncos choose to look for a fullback from their current stable of backs, Thompson could be a viable candidate, given his skills with the football, power and blocking ability. He uses his 225 pounds to maximum effectiveness.

Some of the best Broncos fullbacks in the zone-blocking era were once tailbacks, either in college or the NFL; that group includes Howard Griffith, a record-breaking runner at Illinois, two-time 1,000-harder Mike Anderson (who eventually went back to running back after lining up in front of Clinton Portis in 2002-03) and Cecil Sapp, a Colorado State product who, like Griffith, racked up big numbers in college. So it would not be unprecedented.

But Thompson was so effective in limited action -- he averaged 5.0 yards per carry and picked up one first down every 3.18 carries -- that it might not take a look at fullback for him to get extensive work.

**

JEREMY STEWART** Games played/started:6/0
Snaps:11
Contract:Expires after 2015 season

A promotion from the practice squad gave Stewart a handful of opportunities in December after Thompson began to struggle with hip and knee injuries. He averaged 3.7 yards per carry on 6 rushes, with 16 of the 22 yards he gained coming on one run at San Diego in Week 15.

KAPRI BIBBS
Games played/started:0/0
Contract:Signed to a reserve-future contract after the season.

Bibbs spent four weeks on the 53-man roster, but never saw the field. His nose for the goal line in the preseason (three touchdowns in 19 carries) and his ability to post a solid 4.4-yards-per-carry average through heavy traffic will earn him a solid look, but in a crowded field, he will need a big offseason to separate himself.

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