As for why Cora left Porcello in, got to remember you've got ERod going tomorrow. You have to plan on 3-4 bullpen innings for that start. (well, its the only thing I can come up with).
I think Eck is right though, Porcello was sick or something. He's had some bad games but there was nothing tonight. Every pitcher has those games. Tonight was one of Porcellos.