The Raiders have officially activated 2017 second-round pick Obi Melifonwu from injured reserve, the team announced Saturday afternoon. The safety will make his NFL regular season debut Sunday night when Oakland (3-5) faces Miami (4-3) at 5:30 p.m. PST. Melifonwu injured his leg during preseason and missed the first eight games of the year as a result. He’s practiced for three weeks, and is fully healthy to see the field at Hard Rock Stadium against the Dolphins. Where Melifonwu might play, though, is yet to be seen. He practiced with the cornerbacks in individual drills during open practice Thursday. Coaches and teammates also like his ability to cover tight ends. “Crazy athletic,” Raiders’ quarterback Derek Carr said Wednesday. “I think what he’s going to be really good at is being able to man-match tight ends. I really think that’s an advantage for him. Usually as a quarterback you see a safety and tight end. We like that. But Obi is the kind of guy who’s fast, he’s explosive. He’s strong and he really works hard. The Raiders waived/injured cornerback Demetrius McCray in a corresponding move to Melifonwu’s promotion, and two other corners will not play Sunday. David Amerson (foot) and 2017 first-round pick Gareon Conley (shin) have already been ruled out.