McCaffrey sat out most of training camp and did not play in the preseason due to a calf injury that head coach Kyle Shanahan announced on August 6.

The threat level seemed low, however, as Shanahan said a few weeks later that he wasn’t worried about McCaffrey’s readiness as he dealt with the injury. There seemed to be bigger problems looming, namely left tackle Trent Williams sitting out and wide receiver Brandon Aiyuk sitting out due to contract disputes.

But those matchups both came to an end before Week 1, with Williams and Aiyuk playing in the team’s 32-19 win over the New York Jets on Monday night football.

McCaffrey, surprisingly, didn’t, and he probably won’t for a while.

Jordan Mason filled in as San Francisco’s RB1 in his stead, exploding for 152 yards and a score on 29 touches. It was a stellar prime-time performance that’s good news for the 49ers, who are enduring a stretch without their most dangerous weapon, but there’s still nothing that can replace everything the versatile McCaffrey, a two-time All-Pro and one of the NFL’s best pass-catching backs, brings to the table.

Deebo Samuel will likely need to spend more time in the backfield, as he did Monday, to fill the receiving void there. Additionally, backups Isaac Guerendo and Patrick Taylor (three offensive snaps combined in Week 1) will need to be used more often to keep Mason fresh in his potential new workhorse role.

The 49ers play the Minnesota Vikings, Los Angeles Rams, New England Patriots and Arizona Cardinals in their next four games. If CMC spends the minimal amount of time on IR, he could return for a Thursday night showdown against the Seattle Seahawks on Oct. 10.

The two games San Francisco has between that game and a bye in Week 9 are home games against the Kansas City Chiefs and the Dallas Cowboys.