Over the next two weeks, we will take a position-by-position look at where the Vikings stand heading into the offseason after their 7-9 season in 2014. Today, we tackle the running backs.

The running back position figured to be the least of the Vikings' worries heading into 2014, but it quickly became their biggest headache when perennial Pro Bowl back Adrian Peterson was charged with child abuse down in Texas two days before their second game of the season.

Peterson would not suit up again in 2014, leaving a sizable void in the backfield as offensive coordinator Norv Turner had built his offense around Peterson and the power running game. Matt Asiata got the first crack at replacing Peterson, but after a few starts the team went with rookie Jerick McKinnon, a more explosive athlete. McKinnon surprised by rushing for 4.8 yards per carry. But after 538 yards on 113 carries, he was lost for the season with a back injury.

The Vikings finished the season out with a three-man committee of Asiata, Joe Banyard and Ben Tate, whom the team claimed off waivers from the Browns and then released a few weeks later.

The Vikings ranked a respectable 11th in the NFL with 4.4 yards per carry without Peterson. But the 29-year-old was missed, and his uncertain future will be the story of the offseason.

ONE REASON FOR OPTIMISM: Questions remain about McKinnon's ability to be an every-down runner, but the third-round pick out of Georgia Southern showed that at the very least he is capable of playing a large role in a backfield committee, an approach the Vikings could soon adopt. He has the wheels to get to the outside and he can be a receiving weapon out of the backfield. He also showed at times that he may have the willingness and power to run between the tackles some, too.

ONE REASON FOR CONCERN: It's a big one. The Peterson era in Minnesota may be over, and it has more to do with his contract than his legal issues. Both head coach Mike Zimmer and general manager Rick Spielman have said they would like to have Peterson back in 2015. But Peterson, who turns 30 in a few months, will carry a cap hit of $15.4 million, a league-high for running backs. And in an ESPN interview he scoffed at the suggestion that he take a pay cut to remain with the Vikings. Can he and the Vikings find common ground? Or is Peterson ready for a fresh start elsewhere?

GRADES WITH A GRAIN OF SALT: Since the Vikings (understandably) won't make their player grades public, we turn to Pro Football Focus, whom some players and coaches have been critical of. For context with these grades, a grade of 0.0 is considered average. Positive grades are good. Negative grades are not. There was a lot of red when looking at these backs. Asiata had one of the NFL's lowest grades at negative-10.0. McKinnon was a negative-1.6 (mostly due to a poor grade in pass protection). Tate was a negative-1.3. And Peterson was a negative-0.2 in one game. Banyard led the tailbacks with a plus-1.9 grade in limited action. Fullback Jerome Felton was a plus-3.7.

STAT THAT STANDS OUT: 336 — yards after contact for Asiata. That means 234 of his 570 yards came before contact, an average of just 1.43 yards before contact per carry for the plodding back.

POTENTIAL DEPARTURES: If Peterson does return to the team in 2015, he will be lining up behind a new lead blocker. Felton, seeing the writing on the wall, has said that he plans to opt out of his contract next month to become a free agent. Felton is a good blocking fullback who should find work elsewhere, but $2.5 million would have been a lot to pay for a player at a position used sparingly.

OFFSEASON LEVEL OF NEED: High, if Peterson does not return. McKinnon showed promise and the Vikings like Asiata because he is a selfless player who can do a bunch of things for them. But as we saw in 2014, losing Peterson would leave a sizable void. If the Vikings need to replace Peterson, look for them to do it in the draft. Spielman recently remarked that there are a lot of talented running backs in this draft class, and from a value standpoint, it makes more sense for the Vikings to spend a pick on a young back instead of shelling out cash for a veteran with more tread on his tires.