The Raiders placed Gallup on the reserve/retired list Wednesday, Adam Schefter of ESPN reports.
Gallup surprisingly retired as training camp kicked off for Las Vegas, after having signed a one-year, $3 million contract with the team during the offseason. The 28-year-old wideout played all six seasons of his NFL career in a Cowboys uniform, and injuries seemed to derail him after a promising 66-1,107-6 receiving line in Year 2. Former teammate Dak Prescott praised Gallup following his retirement, per Patrik Walker of the Cowboys' official site, saying "he was huge for my career."