Should really include disguised toasts' video about this https://www.youtube.com/watch?v=QSGH40jokoE
"Transform to gain"Problem solved.
Uhh, everything in that GitHub post is explained by Battlecries always triggering before the minion with the Battlecry actually lands on the board.A Battlecry is like a spell and will always trigger before the minion is actually considered to be on the board.The only thing that can possibly trigger before a Battlecry is the "when the opponent plays a card" effect, such as the one on Fel Reaver.
Here is a very comprehensive advanced rulebook that really helps to understand order of play (including weird wording exceptions). http://hearthstone.gamepedia.com/Advanced_rulebook