The league and the union said the concussion protocol was followed after Dolphins quarterback Tua Tagovailoa hit his head two weeks ago. But his return to that game has prompted a change in the protocol.
Physicians assessing head injuries at N.F.L. games are expected to be able to diagnose concussions. But recent injuries to Tua Tagovailoa raised questions about how effective the doctors can be.
After Miami Dolphins quarterback Tua Tagovailoa sustained two head injuries in the last week, the players’ union removed a neurologist who was part of the process that allowed him to return to the field.
The N.F.L. said its concussion protocols were followed when Tua Tagovailoa hit his head on Sunday. On Thursday, the quarterback left the field on a stretcher after a second head hit.
Miami’s quarterback left Thursday’s game on a stretcher after his head was slammed to the turf for the second time in five days. The players’ union has asked for an investigation of his team’s handling of the concussion protocol.