Overboarding

Overboarding is the sideboarding mistake of swapping out too many cards between games, usually because you can rather than because you should. A player brings in six or seven sideboard cards against a deck that only needed two or three, and ends up with a worse version of their own deck.

It differs from a transformational sideboard, which is a deliberate plan to change what the deck does. Overboarding has no plan behind it. It is a reaction, not a strategy.

Why Overboarding Hurts

Every card you bring in replaces a card the deck was built around. Swap enough of them and you lose the curve, the mana balance and the synergies that made the 60 work in game one.

Sideboard cards are also narrower than maindeck cards. If the opponent adapts or draws differently, those narrow cards can sit dead in your hand.

Overboarding on MTG Arena

Arena only offers sideboarding in best-of-three, and the swap screen makes it quick to move many cards at once. That speed is part of the temptation, especially after a loss when you want to change everything.

Best-of-one players rarely meet the problem, which is partly why it surprises people the first time they move to Bo3.