It's because of pre-existing interference relationships with other stations that had to be moved around. To be specific, this is at least partially the fault of WGBY moving to high-VHF. WGBY was assigned to channel 13. To make it fit there, among other things, stations in New York, Scranton, and Baltmore are swapped to 12. Philadelphia and Martinsburg are swapped to 13. Martinsburg on 13 meant WVEC couldn't be there; it landed on 11. WVEC is already short-spaced to WJZ, but could not be co-channel to WBAL. Thus, WBAL, and not WJZ, was moved onto 12, and WJZ went to 11.
- Trip