"You can't sit here and say it's all on him," Beckham said in reference to the critique of Mayfield, according to ESPN's Jake Trotter. "You have to take a look at everything going on around him. Obviously, he has to play better. I have to play better. Jarvis (Landry) has to play better. (Nick) Chubb. We all have to do better."
Beckham and Mayfield have both struggled so far in 2019, with the latter failing to build upon his successful rookie campaign.
Mayfield is tied with Jameis Winston for the most interceptions in the league with 12.
Beckham, the Browns' marquee offseason acquisition, has one touchdown reception through seven games. His yardage total sits at 488, but it was inflated early in the season by an 89-yard catch-and-run.
"Can't sit back and be like, 'It's Baker's fault.' I feel like that's the easiest thing for us to do," Beckham added. "I've been in situations where one person is getting the blame. And the rest of the people are quiet to kind of stay out of the fire. I'm going to jump in the fire with him. I'll be the first one. Some of these losses are on me. I need to be in the right place at the right time. I'm going to do better.
"I'm going to be the first one here to defend him every single time," the 26-year-old wideout said of Mayfield. "I've always got his back."
Beckham became famous for his sensational catches with the New York Giants, but he hasn't made too many of them for the Browns, who sit at 2-5 entering Week 9.