Yeah when you see a team that goes 4-44 last 3 years and then under 5.5 is + money you should definitely do a deep dive into why that is rather than just snap take the Browns under because the line seems so bizarre. They did improve at QB almost by default, they got some really good WR's especially if Gordon can stay out of trouble, the defense was not atrocious on a yards per play basis last year and they have some good young guys.
But it's hard to see them winning 6 games with that schedule. It wasn't like they went 1-15 last year but lost 10 close games. They lost 5 games you would consider close to the Titans/Jets/Steelers/Packers/Colts. And the last 3 didn't have Ben/Rodgers/Luck respectively. And I believe it was Mariota's 1st game back from injury and he was severely limited.