Firefly would have been AWESOME if they had actually aired the pilot episode first.
Happened with Star Trek, too. The suits wanted a "bug-eyed monster" (BEM) in the first show to air, so we got "The Man Trap" - a nice little Dr. McCoy story, but "Where No Man Has Gone Before" would have been a much stronger first chapter and gave the new audience a better idea about what Star Trek was all about.
In Firefly's case, the powers that be wanted more action, so "Train Job" was aired first.
In a classic example, Firefly was "too good" to be on television at that time. Ironically, with the much better products coming out of the cable networks now, it might have survived today. (Although for every Breaking Bad, GoT, etc., we get 3 shows like Buckwild, Kardashians or Honey Boo Boo.)