Ok first it would help if people actually understood that all of things that happened to Firefly happen to many shows.
First Firefly wasn't a tightly scripted serial,and even some serials do get run out of order. In other words, one episode didn't directly tie to the next.
Yeah the pulot was aired last, but there are may shows where they never air the pilot (the reason they did was most likely just to have something to show, that didn't cost them anything else for a property that they were no longer going to produce).
Fox makes a tremendous amount of money (plus great ad time at the most sought after demo's Males 18-34 and males 18-49) with Baseball. This consumes a huge part of the Fall schedule. Most of Fox's programming gets preempted at some time (and sometimes often) during this time of the year.
Many shows get changes of schedules where they move from night to night or to a different time slot.
Again you are looking at one show. The studio has to look at really 6 nights and whats best for those nights. They also get extremely detailed demo breakdown (age, gender, income) and most of that we never saw) and that plays a huge part.
Promotions, the show got tons. It started as one of the most promoted shows on that season for Fox. And when it couldn't hold those ratings, the ads stopped (and thats how the business works), you don't throw a ton of money after something that isn't performing (and again we got viewer totals and the 18-49 adult demo, we never saw any more and that could have been a huge, huge factor.