The 49ers will be without running back Raheem Mostert for the remainder of 2018 after he fractured his right arm in the third quarter of the 34-3 blowout over the Oakland Raiders on Thursday, coach Kyle Shanahan said Friday.
Mostert was scheduled for surgery on Friday, becoming San Francisco’s second running back in 2018 to get placed on season-ending injured reserve. He’ll join starter Jerick McKinnon, who sustained a torn anterior cruciate ligament in his knee a week before the season opener.
Mostert’s injury came in the third quarter shortly after he weaved down the sideline for a 52-yard touchdown. The run was the longest run of Mostert’s career and his first NFL score. He led the team in rushing with 86 yards on just seven carries.
In addition to emerging as a speedy threat for Shanahan’s offense — he had 250 yards in his last four games on just 28 carries, good for a 8.9-yard average — Mostert was the 49ers’ best special teams player, particularly for his work as a gunner on punt coverage.
“I think for the two years we’ve been here, I think Raheem’s been one of the best special teams players in the league,” Shanahan said. “... And what he’s done for us on offense just in these three weeks has been huge. He’s really taken a step up.“
The 49ers enter Week 10 against the Giants with the league’s sixth-ranked rushing attack, despite losing McKinnon and his backup, Matt Breida, dealing with ankle, knee and shoulder injuries throughout the season. Mostert was a big reason for that, starting with the Monday night game against the Packers on Oct. 15 when he rushed for 87 yards on 12 carries.
That came a week after he struggled to replace Breida in a loss against the Cardinals, when he gave up one of the team’s five turnovers with a lost fumbled on his first carry of the game.
“He’s gotten his opportunity with some injuries and he faced some adversity right away when he got his opportunity with his turnover, and he’s completely bounced back and made himself a hell of a back,” Shanahan said.
“We all know that he’s made this team because of special teams. But, these last few weeks, he’s definitely made this team regardless of special teams. He’s been very good on offense. So, it’s going to be a huge loss for us, but it’s going to open up some opportunities for other people. Just like some opportunities were opened up for him.”
The 49ers have two running backs on the practice squad, Matt Dayes and Jeff Wilson Jr., who could take Mostert’s spot on the active roster. And it’s likely Alfred Morris could see his role expand again after Mostert took over his carries in the past month.
San Francisco also lost undrafted rookie Emmanuel Moseley to a season-ending dislocated shoulder, Shanahan said. Moseley is expected to have surgery Thursday. Moseley was promoted to the active roster hours before Thursday’s game to provide depth and play on special teams. He suffered the injury during his first and only NFL tackle on a kick return, which was just his third play of the game.
Moseley was originally signed a rookie free agent from Tennessee and spent most of the offseason program and training camp playing slot corner.