Dexter McDonald is a larger corner with good athleticism. He stands at 6'1, 200lbs and brings speed too along with him having run a 4.42 40. He lasted this long because he is a raw athlete who will need to be coached up considerably. Still, he has two things that can't be taught with his size and athleticism.
If McDonald can improve in his aggression against the run and take on blockers better he can battle for a roster spot on this Raiders team. Reggie McKenzie loves tall corners and clearly Dexter fits that bill. He will need a lot of work but he is not a bad project pick for the Raiders.
The other part about how raw Dexter McDonald is comes via his initial college experience. He was only at Kansas for two seasons, before that he started out at the JUCO level on the Butler Bulldogs team. He needed to improve his grades before getting to a major school but he put the work in and managed to be a contributor for the division one Kansas Jayhawks by the end of his college career.
Here is a highlight video to get to know the new Oakland Raider a little bit better as well.