Mono-Blue Faeries is a tempo deck built around cheap evasive threats and Counterspell/Spellstutter Sprite, and doesn't present strong graveyard synergies for us to attack, so this is a very light sideboard swap. Relic of Progenitus still comes in as a cheap artifact that can pressure any incidental graveyard value while drawing a card when sacrificed, and is low-cost enough not to disrupt our main plan. Structural Distortion has no good targets since they run no artifacts and no relevant nonbasic lands, so it's the clear cut. Otherwise we rely on our bigger creatures and removal like Boarding Party and Avenging Hunter to outsize their small flyers.