SANTA CLARA -- Kyle Shanahan took every precaution Saturday night, sitting 18 healthy players for the 49ers' preseason opener against the Dallas Cowboys at Levi’s Stadium.
But that didnt prevent the team from sustaining injuries to two players who were expected to hold down significant roles this season.
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Here are three takeaways from the 49ers’ first exhibition game of the summer, a 17-9 win over the Cowboys:
O-line depth takes an enormous hit
Shon Coleman was slated this season to serve as the backup at both offensive tackle positions. If a replacement was needed at any point for Joe Staley or Mike McGlinchey, Coleman would be the guy.
Now, the 49ers certainly will not have Coleman for a large portion – if not the entire – regular season. Coleman went down in the first quarter with a right ankle injury that warranted the use of an air cast to stabilize his leg, and he was carted off the field.
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Rookie Justin Skule started at right tackle, and becomes a serious contender to take over that role. The 49ers also could re-sign Garry Gilliam, who served as their backup tackle the past two seasons.
Running back and core special-teams player Raheem Mostert also exited in the first quarter with a concussion.
Backup QB competition begins
The 49ers hope their backup quarterback does not step on the field once the regular season begins. But Nick Mullens and C.J. Beathard will see plenty of action in the preseason as they compete for the job behind Jimmy Garoppolo.
Mullens was chosen as a team captain for Saturday's game after finishing last season with eight consecutive starts. He played the entire first half before turning things over to Beathard, who sustained a right hand injury in the fourth quarter and came out of the game.
Mullens completed 11 of 17 passes for 105 yards and one touchdown with one interception. Beathard completed 13 of 17 passes for 141 yards and one touchdown with one interception.
Samuel, Hurd separate from herd of receivers
Trent Taylor has been the 49ers’ most consistent receiver in training camp. But he underwent foot surgery Friday, and is expected to be out until early in the regular season.
The 49ers still are waiting for most of their receivers to step up, but rookies Jalen Hurd and Deebo Samuel appear to be coming along just fine. Hurd, a third-round draft pick, caught two touchdown passes, and Samuel, a second-round selection, had two catches for 61 yards, including this 45-yarder.
Hurd is new to the position. He spent three seasons as a running back at Tennessee before transferring to Baylor to play receiver. On Saturday, he showed his running back skills as a receiver, lining up in the slot on the left side and catching a pass from Mullens on a crossing route. Hurd then turned up field and flattened Cowboys safety Kavon Frazier at the goal line for a 20-yard touchdown.
Hurd also hauled in a 4-yard TD pass from Beathard over a Dallas defender.
The 49ers failed to hold onto several catchable passes, the most glaring of which was a Kendrick Bourne drop of a Mullens pass in the second quarter.