With Christian McCaffrey out, Jordan Mason was a revelation. He has been one of the NFL’s best running backs.

Can the San Francisco 49ers get similar production out of their third running back on the depth chart? They had to wonder for a while on Thursday night.

Mason was off to a good start on Thursday night when he was tackled and immediately grabbed at his shoulder area in a game against the Seattle Seahawks. He stayed down for a while while athletic trainers tended to him. Mason went back to the locker room and the 49ers said he was questionable to return with a shoulder injury.

The good news was that Mason returned for the second half, though he went to the sideline after just one carry and was moving his injured arm to get loose. Isaac Guerendo came in when Mason exited, and Patrick Taylor Jr. came in on the 49ers’ first drive of the second half when Guerendo needed a rest. Mason didn’t come back for the rest of that drive after getting in just one play. Mason didn’t return for the rest of the third quarter.

Mason’s injury was worrisome for the 49ers because they were already missing McCaffrey. Not many teams have a rock-solid third running back option on the roster, though the 49ers’ scheme seems to make everyone better. Rookie Guerendo is behind Mason on the depth chart. He’s an athletic fourth-round pick but had just 41 career yards before Thursday. Taylor is behind Guerendo. He hadn’t had a carry all season before Thursday. Deebo Samuel Sr. also takes snaps at tailback, but the 49ers wouldn’t want to turn him into a full-time tailback.

The 49ers had perhaps missed McCaffrey in a few ways, but Mason had replaced most of his production. He was second in the NFL in rushing yards to only Derrick Henry after five weeks. Mason had 536 yards, more than 100 yards more than any back other than Henry.

McCaffrey has been out every game this season due to a calf/Achilles injury. He’s supposed to return at some point this season. The 49ers will hope Mason’s injury isn’t a concern before McCaffrey can come back.