Mayfield started the first five games this season, and they did not go particularly well. He had four touchdowns, four interceptions, and a 71.9 passer rating in those five starts before he was injured against the 49ers. He played better in the second half against the Bengals two weeks ago in relief of Walker, throwing for 155 and two touchdowns in the second half. But even he admitted that was against some passive Bengals coverage (since they were up 35-0 at halftime when Walker was pulled after two interceptions).
But he’s also been supportive of Walker when he was serving as the backup, and said repeatedly he wanted to be a part of wins. That’s why his viral helmet-less celebration Thursday night (when he exchanged head-butts with linemen coming off the field) appeared to be in character.