Oklahoma quarterback Dillon Gabriel entered concussion protocol against TCU, putting his status for next week up in the air. FORT WORTH, TX — Oklahoma’s nightmare scenario struck on Saturday. Down 24 points to the TCU Horned Frogs at Amon G. Carter Stadium, OU quarterback Dillon Gabriel fell victim to a late hit from linebacker Jamoi Hodge. Penalty flags littered the field for a targeting call, but the damage had been done. Gabriel left the game with 9:39 remaining in the second quarter, and now his status for next week’s Red River Rivalry is in question. “He’s under concussion protocol,” Venables…