So WN has only increased service "minimally" in PIT, whereas they can't add flights fast enough at PHL. Is that correct? Strange, there are plenty of gates available at PIT, no?....
yes. SW sees what US and any other airline have seen. PIT doesn't have the O&D to support a big operation. US was succesfull because PIT was a connecting hub. I don't have the hard numbers, but did O&D traffic EVER outnumber connecting traffic there?