OKLAHOMA CITY — Inside the cramped Golden State Warriors locker room here late Tuesday night, there was deflation bordering on a sense of utter disbelief. Players dressed in silence, blankly staring into smartphones, looking for answers, or perhaps it was sympathy.

Andre Iguodala slumped in his seat, wearing a yellow T-shirt that read, “Strength in Numbers.” Except the numbers were all trending the wrong way for the Warriors, the defending N.B.A. champions, who were suddenly in a three-games-to-one Western Conference finals ditch, looking up at an Oklahoma City Thunder team that had taken more than just two games in successive blowouts at Chesapeake Energy Arena.

Within 48 hours, the Thunder had stolen the Warriors’ identity — a team all season tagged as irrepressible, unstoppable and irresistible, and now just bewildered by the 28- and 24-point beat-downs they’d had to endure.

Their record-setting 73-victory season was officially on the brink, and no quantity of pronouncements that the series wasn’t over could call into dispute the Thunder’s budding ascendancy, or Russell Westbrook’s dominance, largely at the expense of a struggling Stephen Curry.