The San Francisco 49ers have made the decision to place star running back Christian McCaffrey on injured reserve after he experienced calf soreness and Achilles tendinitis, sources have revealed to ESPN's Adam Schefter. McCaffrey is expected to miss a minimum of four games, including Sunday's highly anticipated matchup against the Minnesota Vikings. Although there is a possibility of a return on October 10 for a Thursday Night Football game against the Seattle Seahawks, it is not guaranteed.

San Francisco coach Kyle Shanahan acknowledged the possibility of placing McCaffrey on injured reserve, which had been previously hinted at when the running back's Achilles did not respond well to limited participation in practice on Thursday. Shanahan stated that McCaffrey's Achilles had worsened on Thursday, prompting the discussions that led to the decision to shut him down in hopes of allowing the flare-ups to settle.

One of the most challenging aspects of McCaffrey's injury has been its unpredictability. On some days, the running back feels good and is able to practice, while on others, he experiences significant pain. This inconsistency has undoubtedly been frustrating for McCaffrey, who was named the NFL's Offensive Player of the Year in the previous season.

McCaffrey, who joined the 49ers via trade in October 2022, had a remarkable track record of only missing one out of 33 possible games over the past two seasons, including the postseason. However, injuries plagued his time with the Carolina Panthers, resulting in him missing a combined 10 games in 2020 and 2021 due to various ailments.

With McCaffrey sidelined, the responsibility of leading the running back duties will fall upon Jordan Mason. Mason made his first career start last week against the New York Jets and performed admirably, recording career highs with 28 carries for 147 yards and a touchdown. Against the Jets, wide receiver Deebo Samuel Sr. also served as Mason's backup, contributing eight carries for 23 yards and a touchdown.

The 49ers will also have other running back options at their disposal. Rookie Isaac Guerendo and fourth-year veteran Patrick Taylor Jr. are available on the active roster, while fifth-year veteran Ke'Shawn Vaughn is on the practice squad.

Although McCaffrey's absence will be felt by the 49ers, the team remains focused on making the most of this situation and securing victories in his absence. The hope is that McCaffrey will make a successful return after his recovery period and play a significant role in the team's season moving forward.