But both the Browns and the 2018 No. 1 selection fell far short of expectations, and Mayfield said Friday the team's failures impacted him.
"Having success all through high school and college, and having that standard so high, and then (last year) not nearly as much success as I'm used to - so I would say I lost myself," said Mayfield, according to ESPN's Jake Trotter. "Not having that success, not finding out what was working, I think I tried different ways of trying to have that success and I didn't find it.
"So I lost myself in that, and I wasn't able to be who I (need to be) for these guys on the team."
In 2019, Mayfield's interception total increased from 14 as a rookie to 21, the third-most in the league. The 25-year-old also threw five fewer touchdown passes and saw his completion percentage fall from 63.8% to 59.4%.
The Browns' 6-10 finish led to the firing of head coach Freddie Kitchens after just one season. Cleveland also parted ways with general manager John Dorsey.
The duo of head coach Kevin Stefanski and general manager Andrew Berry is tasked with making sure Mayfield gets back on track in 2020.
To bounce back following his sophomore slump, the third-year quarterback spent the offseason focused on improving his conditioning.
"I think there was a lot of plays - looking back on last year - physically, I wasn't able to work out as much, being beat up. So I was heavier than I was ever playing before at a playing weight," said Mayfield. "I needed to be able to have the scrambling ability to move in the pocket. It's my job to be in prime physical shape, to show up and do my job on Sundays."