http://www.seagulls.co.uk/news/article/oscar-agrees-three-year-deal-931776.aspx
Last season, we didn't have a manager, we had a head coach, but as Barber pointed out over the summer, the role was essentially the same. So assistant head coach = assistant manager.
What confused me was this bit:
They've both replaced the one guy?
Well, the previous assistant was Sammy Lee. We have been without one since he decided not to join us. Last season, Oscar's assistant was Nathan Jones.