I don't think UA should (or can) compete with WN by offering BE fares. WN's not in the GDS so UA gain's no meaningful advantage in online comparisons. Plus WN doesn't use the unbundled services model the other LCCs do. Go on the WN forum, all you hear is "free checked bags, no change fees"; offering a $4 cheaper fare is not going to bring those pax over to UA. And WN just killed UA intra-California when BE first came out . . . the resultant fare war is still raging.

I'm not sure what the fare differential Y=>BE should be, but $4 is ridiculous.