When you operate multiple fleets you can only furlough as fast as you can hire.
AA was trying to furlough faster and started running into problems. What happens in clumps of pilots are at various seniority levels. At AA, a well managed company, for example they almost shut down the A300 in NY with what they were planning to fulough, and had to rescind the furloughs to keep the airplane flying as they couldn't retrain fast enough. They can still furlough later if they want, but not faster than they can train the shifts throughout the fleet.
AA is a well managed company. I suspect that USAIR furloughed all the copilots in a particular fleet faster than they could downtrain and screwed themselves. They are the worst managed company in America after all, but go ahead and blame the pilots. With them reducing flying it shouldn't be possible for pilots to leverage a company like that.
Wino