When UAL oversells, the pax don't pay for a ticket on us...UAL pays us to put them on, and that's at the FIM (Flight Interruption Manifest) price (uber-expensiveola, or so I have been told), but we pay the same vice-versa.
As far as EMB's parked, 2 were parked, but not due to lack of pilots. I believe they reduced the pilot lines in anticipation for possible pilot departures, but the main reason for the parked EMB's is due to engine overhauls. 1 is close to a heavy check, thus 'donated' its engines to the last aircraft that was in for its heavy. The 2nd had an engine due to overhaul as well. We currently have 5 running, and 1 waiting for engines.
Porcupine: The complaints are that they miss your Fire Detection expertise, and routine greasers!