Mayfield wasn't named the Browns starting quarterback until Week 4.
It's official. Baker Mayfield has had a record-setting rookie campaign.
The Browns' first-year signal-caller set the NFL single-season rookie record for passing TDs on Sunday when he tossed his 27th touchdown of the season on a one-yard completion to receiver Antonio Callaway.
It marked Mayfield's third touchdown pass of the game.
Mayfield broke the previous single-season rookie record previously held by Peyton Manning (1998) and Russell Wilson (2012), who each threw 26 touchdowns in their first NFL seasons.
The Browns selected Mayfield out of Oklahoma with the first pick of the 2018 NFL draft. He wasn't named Cleveland's No. 1 quarterback until Week 4, when he made his first start against the Raiders in place of Tyrod Taylor.