SANTA CLARA, Calif. -- Since Kyle Shanahan took over as head coach in 2017, the San Francisco 49ers have had a different leading rusher in each of those five seasons.
After starting running back Elijah Mitchell sprained the MCL in his right knee in Sunday's loss to the Chicago Bears, which is expected to keep him out for about two months, there's a realistic chance that streak will continue.
Such is life in for the 49ers, where little-known running backs emerge as focal points nearly every season. It's why the Niners have made it an organizational priority to add running back depth every offseason either through free agency, the draft or both.
"I think we've gone through at least four throughout a year and we're already at that again," Shanahan said. "And that's why you can never have too many of them. Sometimes it feels like we have a lot, and very quickly it now feels like you don't because those numbers end fast."
The bad news for the Niners is they lost their clear-cut No. 1 back in Mitchell, a promising young player who was off to a good start and poised to become the first 1,000-yard rusher in Shanahan's San Francisco tenure.
The good news, if there is such a thing, is that no team in the league has proved better at adapting to running back injuries. That's how the likes of Carlos Hyde, Matt Breida, Jeff Wilson Jr., Raheem Mostert and Mitchell -- a second-round pick, three undrafted free agents and a sixth-round selection, respectively -- have emerged as the team's leading rusher in each of the past five seasons.
Since 2017, the Niners rank 11th in the NFL in rushing yards and yards per carry while ranking eighth in attempts. Over the past three seasons, they're sixth in rushing yards and 13th in yards per carry. That production, despite the lack of a consistent primary option in the running game, buoys the Niners' confidence that they can keep running it well sans Mitchell.
"We hope to have better luck with that in the future, but hopefully we can hold down the fort here a little bit and when Elijah comes back, he's coming back to a better team and helping us make a run," Shanahan said.
When and if Mitchell comes back, the Niners should have a much better idea of just how deep this year's stable of running backs is. In August, the team released backs JaMycal Hasty and Trey Sermon, both of whom played in 2021 and were promptly claimed on waivers by the Jacksonville Jaguars and Philadelphia Eagles, respectively.
While neither Hasty nor Sermon had much success, they would have brought some experience to a running back room that has only two players -- Wilson and veteran Marlon Mack, who was signed to the practice squad on Tuesday -- with NFL carries.
That experience is why Wilson will get the first crack at replacing Mitchell. Wilson appeared in nine games last season after recovering from a torn meniscus in a knee. When he did play, he didn't look much like the player who led the team in rushing in 2020. Another year removed from that injury, Wilson appeared to be closer to his former self in training camp, though he managed just 22 yards on nine carries after replacing Mitchell at rain-soaked Soldier Field on Sunday.
"We've always been comfortable with Jeff, just because of his experience and what he has done here," Shanahan said. "We know what we're going to get."
The Niners don't know what they're going to get from the two backs behind Wilson, however. Third-round pick Tyrion Davis-Price and undrafted rookie Jordan Mason have yet to play a regular season NFL offensive snap but landed roster spots over Hasty and Sermon, a clear sign that the Niners believe in what they could bring to the table.
Davis-Price and Mason are both bigger, more physical backs than the speedy likes of Mostert and Breida. On Sunday, Mason was active ahead of Davis-Price in part because of his contributions on special teams. That doesn't necessarily mean he will be ahead of him when it comes to rushing opportunities, but it's the only data point to work from thus far.
According to Shanahan, the biggest thing for both rookie backs is learning how to do the little things -- blitz pickups, route running, even run blocking -- that happen when they don't have the ball. Shanahan said both players will have to "grow up fast" and the pressure will be on because they will be getting opportunities sooner than later.
"That's really the toughest thing for a running back in this offense," fullback Kyle Juszczyk said. "The transition from college to the NFL, as far as just carrying the ball, is really not a huge transition. And that's why you'll see a lot of successful rookies in the NFL at the running back position. But it's that stuff when you don't have the ball ... you get asked to do some things that maybe I would be doing as a fullback."
The 49ers also have other options to energize the run game. Both were on display in the loss to the Bears, as quarterback Trey Lance and receiver Deebo Samuel were the top two in rushing yards. Lance's rushing attempts will be harder to project because some will happen outside the structure of the play, but the Niners won't shy away from asking him to gain yards with his legs.
It was an injury to Mitchell (and other backs) that pushed Samuel into an expanded rushing role last season, and though Shanahan insisted that the running backs must still produce, Samuel's use as a running back will remain a staple in the offense with Mitchell out. That's just fine by Samuel, who remains comfortable as a "wide back."
"It just feels the same," Samuel said. "I've been doing it for a long time, so I don't see it different. Once I see a hole, I'm gonna hit it and whatever happens, happens."