According to ESPN's Rich Cimini, Darnold took responsibility for the defeat: "From my point of view, I just have to play better, simple as that. It's not acceptable, the way I played. I know that, and I have to take it like a man. I feel like I'm responsible for some of the stagnant offense we had. I just have to play better; that's it."
The 21-year-old went 15-of-31 for 169 yards with no touchdowns and two interceptions.
Both of Darnold's interceptions came in the fourth quarter, and the former USC standout acknowledged that he needed to make better decisions with the football: "I felt really comfortable throughout the whole game. I just made stupid mistakes in the fourth quarter and missed opportunities throughout the whole game. I have to play better, and that's on me."
While Darnold struggled, 2018 No. 1 overall draft pick Baker Mayfield was excellent for Cleveland after replacing the injured Tyrod Taylor.
Mayfield entered the game with the Browns trailing 14-0, and he led them to a come-from-behind victory, marking their first win in 635 days after going 0-16 last season.
The reigning Heisman Trophy winner went 17-of-23 for 201 yards with no touchdowns or picks in out-dueling Darnold.
A closer look at Darnold's numbers show he had difficulty on throws beyond the line of scrimmage.
Per ESPN Stats & Info (h/t Cimini), Darnold was 6-of-8 for 63 yards on screen passes and just 9-of-23 for 106 yards and two interceptions on all other passes.
It represented a step back.
Darnold threw for 198 yards with two touchdowns and one pick in a Week 1 win over the Detroit Lions before throwing for 334 yards with one touchdown and two interceptions against the Miami Dolphins last week.
His next chance to atone for Thursday's poor showing will come Sept. 30 when the Jets travel to Jacksonville to take on the Jaguars and their dominant defense.