It isn't surprising that Colorado took a step back last season after winning the Pac-12 South title two years ago. Still, the Buffaloes couldn't help feeling disappointed at experiencing a slide that took them from first back to another last-place finish.

Colorado won just two Pac-12 games in 2017 and finished with a losing record for the 11th time in the last 12 seasons. The Buffaloes struggled to finish drives, producing just 26.4 points per game to rank 11th in the league in scoring offense. Stopping opponents also became an issue. Colorado yielded 450.6 yards per game to rank ninth among Pac-12 teams in total defense.

Climbing the ladder in the division again will not be an easy task. The Buffaloes must replace their top running back, several key receivers and their leader in the secondary from a year ago. These are critical holes for Colorado to fill as it begins spring football on Friday.

5 Storylines to Watch in Colorado’s Spring Practice

1. Can anyone fill the shoes of Phillip Lindsay?

It isn't a stretch to say that Lindsay carried Colorado’s offense last fall. He totaled 1,474 yards and 14 touchdowns on 301 carries in his senior season. Lindsay accounted for at least 90 percent of the total carries and total rushing yards among the team's running backs. Replacing him will be a chore.

Beau Bisharat, Donovan Lee, Kyle Evans and Alex Fontenot are all in the mix to take over as the next featured back. Bisharat saw limited action a year ago behind Lindsay, tallying 61 yards on 21 carries during his sophomore campaign. Evans and Lee are both seniors. Lee redshirted a year ago while Evans struggled to bounce back from a dislocated hip he suffered in the spring. Fontenot is a promising redshirt freshman who impressed on the scout team last fall. This group will have competition over the offseason in the form of Virginia Tech graduate transfer Travon McMillian.

2. Who will step up at wide receiver?

Graduating your three top receivers isn't an ideal scenario for any team. That's the situation the Colorado faces going into the spring. Bryce Bobo, Shay Fields and Devin Ross all ranked in the top 10 in career receptions for the Buffaloes. The trio combined for 1,824 yards and 11 touchdowns on 151 catches last fall.

Seniors Jay MacIntyre and Juwann Winfree will be expected to take on a much bigger load. MacIntyre totaled 396 yards and two touchdowns on 28 catches last season. Winfree came on strong near the end of the season and finished with 325 yards and two touchdowns on 21 catches. He tallied 216 yards over the final two games against USC and Utah. Laviska Shenault Jr. is a deep threat who could rise up to give the Buffaloes another valuable playmaker.

3. Will a new leader emerge in the secondary?

Replacing Isaiah Oliver in the secondary will not be a simple task. Oliver anchored Colorado’s pass defense a season ago, totaling 26 tackles and a pair of interceptions at cornerback. He decided to forego his senior season and enter the 2018 NFL Draft — where Oliver is projected by some analysts as a first-round pick.

Evan Worthington is a natural candidate to step into Oliver's shoes and take on a bigger leadership role. Worthington is a gifted safety who led the Buffaloes with 57 solo tackles and three interceptions in 2017. He has the speed and physical tools to be strong in both run and pass coverage. Dante Wigley and Trey Udoffia also will play bigger roles at cornerback after combining for 73 tackles last season.

4. Can Steven Montez take a step forward at quarterback?

A full season's worth of starting should make a difference for Montez (above, right) in running the offense. The junior posted decent numbers a year ago. He totaled 2,975 passing yards, 18 touchdowns and only nine interceptions while completing 60.5 percent of his attempts. On the other hand, Montez struggled to make big plays at critical times, which made it tough to convert drives in the red zone.

If Montez can take a step forward as a leader in the spring, it can make a difference in improving consistency for the Buffaloes. Montez will be learning from a new quarterbacks coach, Kurt Roper, and can't afford to become stagnant. He has a pair of younger quarterbacks who can push him. Sam Noyer, and Tyler Lytle are skilled enough to lead the offense and either player could get a long look if Montez is inconsistent.

5. How much progress will the defensive line make?

Stopping the run became a major problem for Colorado as last season progressed. The Buffaloes ranked 10th overall in the Pac-12 in rushing defense, allowing 208.0 yards per game. Colorado yielded 882 rushing yards over the final three games alone. A new defensive line coach, Kwahn Drake, and more experience up front should pay dividends this year.

Chris Mulumba and Javier Edwards are returning defensive line starters. The duo combined for 61 tackles a year ago. Redshirt freshman Terrance Lang could be a difference maker. Lang redshirted last season while he bulked up his frame. He's speedy, physical and is drawn to the ball like a magnet. Mustafa Johnson, a gifted junior college transfer, and true freshman Israel Antwine also will be in the mix.

— Written by John Coon, who is part of the Athlon Contributor Network. Coon has more than a decade of experience covering sports for different publications and outlets, including The Associated Press, Salt Lake Tribune, ESPN, Deseret News, MaxPreps, Yahoo! Sports and many others. Follow him on Twitter @johncoonsports.