i think there isnt one thing, there are many:
1. vault and vault management(suicide decks, decissions): i think our vault was pretty good from the start till the end, with a small lack of fire pillars at the end, but with 2 times, playing a suicide deck (against the "correct" opponent at the correct time) made the vault fitting again, for us. a few mistakes, sure, but not that many, other elements made.
2. metagame and opponent analyses: we (entire fire team) often exspect the decks of our opponents very exact, with a few exceptions (then we lost most of the time, like our first light and time matchups, our 2 entropy matches, we played with phase-shields, at round 5, the first time, earth used flying discords, etc.) we also won some matches with the weaker decks, like me against dragoon, round 4, but we also lost with the better decks, like kevkev round6 against $$$/didonko.
this could happen, cause we had very great analyses of every single element, in the element for element thread(
http://elementscommunity.org/forum/index.php/topic,7419.0.html (
http://elementscommunity.org/forum/index.php/topic,7419.0.html)), the earth-thread (
http://elementscommunity.org/forum/index.php/topic,9348.0.html (
http://elementscommunity.org/forum/index.php/topic,9348.0.html)), and others (like before the finals, etc)
3. deck-testing: we tested our decks all the time. before we had our vault ready, we had 11 great decks, and we nearly tested every single deck against possible decks, fine-tuned them to get them ready and most of the time the one, who played the deck, was used to it against most archetypes, he possibly could face.
4. activity: we had to use not a single substitute after round 4. we had matches before that round, your substitutes were very bitter, cause there was the possibility to sub 6 photons once, and 6 immolations from another deck, so we lost an additional powerhouse, cause we had enough - and the right - cards for it, we later got rid off (round 6, gg against zeru and round 7, kevkev against terro, our suicides)
that was very important, cause i think, we played (and lost with/had at the end in vault) about 5 decks with shieldlocks (dim. shield). thanks to our opponents and the possibility, to salvage enough aether pillars and shields.
i hope i havent missed something, not sure, maybe someone from team fire with additional suggestions, but i think thats it. hope that satisfy you.