Luke O’Nien put on another quality performance as Sunderland thrashed Portsmouth on their own turf. The Black Cats didn’t enjoy the best first half display at Fratton Park, but a comical own goal by Pompey put them in the driving seat within half an hour. Sunderland turned it up a gear in the second 45 minutes, with Alan Browne and Romaine Mundle making it 3-0 inside an hour. The Wearside outfit looked like they could score even more as they earned their fourth successive win in the Championship, while they were initially on course to make it the same amount of games without conceding a goal. …