By Mitchell Forde The Carolina Panthers are preparing to take the field Sunday without their starting quarterback. But they haven’t closed the door on Baker Mayfield leading the offense. The Panthers announced Friday that Mayfield will be listed as doubtful for Sunday’s matchup against the Los Angeles Rams. Mayfield has not practiced this week due to an ankle injury, but he “was on the field without a walking boot and did some running and throwing on the side,” according to the Panthers website. If Mayfield is unable to play, PJ Walker will start. The team also elevated Jacob Eason from the pr…