There is lots of logic to how delta uses the buildings. First, Delta was the original developer of terminal A and originally had the whole terminal. After bankruptcy and other downsizing it was reduced to having just the satellite, and then after the NW merger it picked up some gates back at the main building.

Over time, Continental (once a SkyTeam partner) Alaska, Sun Country and now Southwest and WestJet have shared parts of the building.

Today, A1 is a Delta gate primarily assigned to WestJet. A2-A4 are generally used for Delta Shuttle and other small regional jet flights. The rest of the A gates support most Delta narrow bodies up to a 737-900er. You could probably do a 757 if you shut down an adjoining gate. There are 11 gates total in the main building.

Delta has the satellite gates on the left side of the building as you come out of the terminal, five in total. The five gates on the right are used by Southwest. All the wide body flights and most 757s operate from these gates. If I were betting, I'd bet Dublin will depart from the satellite.

Hope that's helpful.