There's no disconnect. They're different flights. With a codeshare think of it like this; they're two different flights, and inventory is separate for each flight. AF can decide what buckets and what price to sell its(AF coded) flight at and DL can decide what price and what buckets to sell its flight(DL coded) at, even though in the end you'll be on the same plane.

Basically DL is selling you a flight they offer that they have no plane to fly it. Thus they send their information over to AF who then flys you on its flight.