Detention Sphere has been an auto-include in decks with White and Blue in them since its printing
Not only can it phase out some of their creatures, but it might also take out one in combat
Granted, the overall historical momentum has been for it to keep moving earlier (understandable since the Summer slot came into existence, and then later into prominence), but clearly WotC is at liberty move the Spring set around at will
If youre playing warriors, this isnt the worst card you could include to get that last bit of damage through
Still, Bark-Knuckle Boxer is relatively strong for its mana value, and I could see its Limited potential
If Blue, Loyal Raptor and Owen Grady, Raptor Trainer are your commanders, your deck may contain cards with green, blue, and/or red in their color identity, but not white or black