EA foots the bill, they make the deals around the product, they make the promotion, etc. the studio makes the game while they do not have to worry about the business side and they get paid in the mean time, which is always nice.
Obviously, this is like that for most studios with most publishers... for better or for worst (would respawn have had the money to hire and retain all the talents if there was no publisher to back them up? maybe not, otherwise they would have remained indy and made all the decisions for themselves).
What I don't like about that kind of deal with third party studios is that one platform owner takes in project that would have been available to others and pay the IP owner to not publish it... it's not very constructive, I would prefer it if they build their own teams and made games that would not otherwise exist for their platform.
