As the 49ers get ready to report to training camp this week, there's one positional battle that everyone from fans to fantasy owners will be playing close attention to, and that's the battle at running back. 

Last year, the 49ers had a grand plan at the position, but that plan went down the drain just before the start of the season when presumed starter Jerick McKinnon tore his ACL. McKinnon, who signed a four-year deal with the 49ers in March 2018, had been the offensive highlight of San Francisco's free agent class. Forty-niners coach Kyle Shanahan added McKinnon because he thought the former Vikings running back would thrive in his offensive system. 

With McKinnon set to return in 2019, you'd think the starting job would be his, but that's not necessarily the case, and that's because Shanahan threw a wrench into things back in March by bringing in Tevin Coleman. The former Falcons running back spent two seasons with Shanahan in Atlanta and is very familiar with the coach's offense. 

With Coleman in the fold, the 49ers will now be going into training camp with three backs who could potentially win the job: McKinnon, Coleman and Matt Breida. Of course, we use the term "win the job" loosely, and that's because all three backs will likely play in 2019, it's just a matter of who gets the most snaps. 

As recently as April, Shanahan didn't seem so sure about who the starter would be.  

"Everyone keeps asking me that like I'm in charge of that or something," Shanahan recently said on the Adam Schefter podcast, via NBC Bay Area. "It's up to the players. They will define their roles. That's kind of what's unique about this."

So who will be taking the most snaps out of the 49ers backfield this year? 

Let's take a look at the contenders. 

Tevin Coleman

Coleman won't be the highest-paid player in the 49ers' backfield this year, but that doesn't mean he won't be able to win the job. As a matter of fact, he might be considered the favorite to see the most snaps this year for two big reasons. For one, he's actually healthy. Everyone else in this competition is coming off a 2018 season where they got extremely banged up. Not only did McKinnon tear his ACL, but Breida also missed multiple games due to injuries. There's also Raheem Mostert, who played in nine games last season before breaking his arm. With everyone banged up, Coleman got a lot of reps during the spring, which allowed him to familiarize himself with the 49ers version of Shanahan's offense. 

Of course, Coleman probably didn't have to learn too much, because he's already spent two seasons with Shanahan. Coleman's first two years in the league came in 2015 and 2016, when Shanahan was the offensive coordinator for the Falcons. Coleman's career-high in receiving yards (421) came in 2016, when Shanahan was calling plays for a Falcons team that went to the Super Bowl. Coleman has also proven that he can take a pounding on the field. In 2018, he carried the ball 167 times for 800 yards. 

Coleman basically fell into Shanahan's lap this offseason and you have to think the 49ers coach will make sure to take advantage of that. 

Matt Breida

After McKinnon went down, Breida came out of nowhere last season to lead the 49ers in rushing. In 14 games, Breida carried the ball 153 times for 814 yards and three touchdowns (To put his yardage total in perspective, he had more yards in 14 games than Coleman or McKinnon have ever had during any single season in their careers). The most impressive part of Breida's performance in 2018 was that no one could tackle him. The 2017 undrafted free agent averaged 5.3 yards per carry, which ranked fourth in the NFL. 

Basically, Breida was so good in 2018 that it's going to be impossible for Shanahan NOT to give him some extended playing time this year. Although Breida did deal with a nagging ankle injury in 2018, that doesn't seem to be bothering him anymore.  

Jerick McKinnon

If Shanahan has proven one thing during his coaching career, it's that he loves utilizing multiple running backs in his system. When Shanahan was in Atlanta, not only did he have Coleman, but he also had Devonta Freeman. One thing Shanahan loves to have in his offense is a pass-catching running back and that's where McKinnon excels. During his four NFL seasons on the field, the former Vikings running back has caught a total of 142 passes, which is exactly 50 more than Coleman has caught in four seasons of action. 

During his best receiving season with the Vikings, McKinnon caught 51 passes for 421 yards. The good news for McKinnon is that he has a slightly different skillset than Coleman, which means there could be times this season where Shanahan uses both backs at the same time. Shanahan is one of the most creative offensive minds in the game, which is probably why he's so excited to have so many options at running back. The one thing Shanahan will definitely be doing with his backs is creating mismatches by taking advantage of their speed. 

"They all can do a bunch of different things," Shanahan told Schefter in April. "The one thing that they have in common is they all run 4.40 or less so I don't have to look back there to see if I have a slow guy or a fast guy, they are all fast."

Although McKinnon should get plenty of playing time this year, it wouldn't be surprising to see him get the fewest touches of the Big Three (Breida, Coleman, McKinnon).  

Others: Raheem Mostert, Jeff Wilson

It's not clear if the 49ers will keep four running backs on their roster, but if they do, Mostert seems like a lock to fill the final role. Not only can he thrive in an offensive role, but he also excels on the special teams side of the ball. During the 2018 season, Mostert carried the ball 34 times for 261 yards before breaking his forearm in Week 9. As for Wilson, although he saw some extended playing time last year due to all the injuries the 49ers were dealing with at running back, it's unlikely he'll be able to crack the roster. The good news for the 2018 undrafted free agent is that he's still eligible for the practice squad, which means he could stick with the 49ers, even if he doesn't make the 53-man roster. Wilson played in six games last year and rushed for 266 yards on 66 carries.