"Everyone keeps asking me that like I'm in charge of that or something," Shanahan recently 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."
The coach's comment means the 49ers' backfield training camp battle should be one of the best in the NFL come August.
One aspect that each player brings to the table is speed, which Shanahan points out should allow him to be fluid with his play-calling without worrying about which back is in the game on any given situation.
"They all can do a bunch of different things," Shanahan said. "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."
Last season, the 49ers saw backs drop like flies due to injury, starting with McKinnon in the offseason and issues plaguing Breida seemingly every week. With four potential ball carriers each week (plus special teams standout Mostert), Shanahan pointed out that the depth might prove prudent.
"They come in different sizes, they do different types of routes," Shanahan said. "We played with four running backs last year so I'm not going sit here and try to think about what to do with four running backs, we might need them all."
Injuries could curtail the rotation this season. Until then, Shanahan seems destined to employ the hot-hand approach to the position.