OK, so here’s what actually happened:
Joe Maddon listed both Evan Longoria and Ben Zobrist as 3Bs for the day, even though he was intending on having Longoria play as a designated hitter. Eric Wedge, that old rascal, waited for Zobrist to take the field before he raised his objection, denying Maddon the ability to fix his lineup card in the most desirable way (losing Zobrist, keeping Longoria). American League rules require the manager to forfeit their DH slot if they switch in a postition player (meaning that double-switches for AL teams turn them into NL teams for the duration of the game). Since Longoria wasn’t the player on the field, it was his slot that had to be adjusted to get the pitcher in the lineup. Sonnanstine was technically pinch-hitting for Longoria, so that was why Longoria was unavailable.
As it turned out, Sonnanstine hit a double, so Maddon did not end up paying for his mistake.