Former San Francisco 49ers wide receiver Michael Crabtree has joined the Oakland Raiders. "It's official," Crabtree wrote on Twitter. "I'm a Raider." Crabtree previously visited the Miami Dolphins. Crabtree has dealt with injuries and is more of a possession receiver now. Crabtree, 27, returned last season after undergoing surgery to repair a torn Achilles the previous year. Crabtree caught 68 passes for 693 yards and four touchdowns. For his career, Crabtree has 347 career receptions for 4,327 yards and 26 touchdowns. Follow me on Twitter: @RavensInsider Aaron Wilson covers the Ravens for The Baltimore Sun