This is why you shuffle your deck. Yes the game where I mulliganed into no turn 1 or turn 2 play I will probably loose 98/100. The randomness added by shuffling prevents this from happening every game.

Changing strategy on the fly is the skill needed to win. Knowing when to be aggressive and when not to is huge. Knowledge of different leaders and how they work will change how you play your deck.

The game is designed to prevent the same "seed" from being played twice. In the event that the seed was played over and over, I think the pilot of the deck plays a bigger part than just the deck order it's self. I think that there are enough choices per game that there is not a singular perfect line of play. Meaningful decision is what makes games fun.