The San Francisco 49ers were absolutely ravaged by injuries last season, which played a massive role in their disappointing 6-11. And once again this summer, the 49ers are once again experiencing medical issues.

The San Francisco 49ers continue to manipulate their roster, as they deal with several injuries at key positions in the preseason.

The 49ers announced a handful of roster moves on Wednesday. They have signed offensive lineman Michael Dunn and wide receiver Malik Knowles to their 90-man roster. They released defensive lineman Demone Harris and waived running back Corey Kiner with an injury designation in corresponding moves.

The San Francisco 49ers have needed an offensive lineman to step up at guard and an undrafted rookie is doing just that through two preseason games.

"If the 49ers want to lighten Christian McCaffrey's workload, they must add a durable running back to the rotation," Moton wrote. "Robinson can grind out yards between the tackles, which would allow McCaffrey to stay fresh for the length of the regular season."

There's no clarity yet on which quarterback will start for the San Francisco 49ers in their final preseason game.

The 49ers wisely have some key veterans, most prominently Nick Bosa, Christian McCaffrey and Trent Williams, on schedules designed to keep them fresh and out of the fray from time to time. Quarterback Brock Purdy is a leader in a more reserved, analytical way. Deommodore Lenoir is stepping up to push the secondary.

Renardo Green and Isaac Guerendo were among those who returned for a practice in which Brock Purdy and Ricky Pearsall continued to connect.

The injury list for the San Francisco 49ers went through a bit of a shuffle with a few key players returning from injuries Tuesday while significant questions remain on several others just a week before NFL rosters will be cut to 53 players.