As advertising budgets become more fragmented, it's easy to imagine a situation in which ad agencies serve primarily to orchestrate production teams, bringing in art directors and copywriters for specific ad campaigns rather than keeping a whole staff on hand.
With more fragmented ad budgets a situation has arisen where ad agencies delegate different teams. 
mnli hypothesis: With more fragmented ad budgets a situation has arisen where ad agencies delegate different teams.  premise: As advertising budgets become more fragmented, it's easy to imagine a situation in which ad agencies serve primarily to orchestrate production teams, bringing in art directors and copywriters for specific ad campaigns rather than keeping a whole staff on hand.