At the risk of being named all sorts of things, i would say there might be some sense to Opa being on the bench.
We are light in the middle this week with no Jnr ... Marata must play in the middle (dont wanna rely on maka and rodwell for big mins) .... marata would normally be the dude to slide to centre IF an outside back gets injured, but thats not an option this week .... so prob need an outside back to cover on the bench.
As for why no Nrown to play decent middle minutes? ..... well f**k me, I dont know - BA you dumb f**k!
I'd like to call you all sorts of things, but I can't remember their names.