The Raiders signed Garbers on Tuesday.
Garbers, an undrafted free agent out of California, spent most of last season on the Raiders practice squad and was elevated to the active roster late in his rookie season when Jarrett Stidham replaced Derek Carr as the starting quarterback. Garbers was surprisingly let go ahead of training camp, but he's back on the squad a week later and will compete with veteran Brian Hoyer and rookie Aidan O'Connell for a backup spot behind Jimmy Garoppolo.