I would not be surprised if a B6 E90 going against a DCI E75 on short/midhaul routes is a unit cost wash. B6 E90s pay mainline wages.
B6 E90 pilot pay scale is quite a bit lower than A320 pilot pay scale. And pilot pay is only a fraction of the overall cost.
Right, AS recently said their regional CASM is twice as high as mainline. That's a pretty good guideline of B6 hs said E90 is 20% higher than A320 series. That would show cost of A320/B738 mainline vs regional is greater than the cost of A320/B738 mainline vs 100 seat mainline.
Think about these ways.
E75 vs E90. Same E-Jet series. They have the same number of pilots and FAs. One has 100 seat and the other has 70 or 76 seats.
Or B717 vs E90 vs E75. Both B717 and E90 are mainline pay scale with about the same number of seats. So given the same airline, they should have comparable costs. If B717 doesn't have lower cost than E75, why would they proactively upgrade routes to B717 when more seats would mean lower yields?
Back on the original topic, do you know why I said I don't think certain yields works for DL?
I've looked at a wide range of low yielding short haul DL routes across their network like LAX-SFO and LGA/JFK-CLT. None of these routes are getting the kind of yield that I'm seeing on BOS-PIT/BUF. That doesn't mean these numbers can't come up, but the current level of yields are not sustainable.