Cleveland Browns offensive tackle Joe Thomas has declared that quarterback Johnny Manziel has proven that he can be a starter in the NFL due to his hard work in the off-season.

The 22-year-old was criticised by his own teammates for his exploits in his first campaign with the club due to his partying antics, which prevented him from earning the starting role.

When Manziel eventually did start due to an injury to Brian Hoyer, he struggled immensely and sustained a hamstring injury, ruling him out for the rest of the campaign.

However, Thomas believes that the quarterback has made major strides in his improvement in the off-season to become a future starter for the Browns.

"He's really proved to a lot of people that this is important to him and he's ready to be an NFL starting quarterback," Thomas told reporters.

"Playing well in the scrimmage tonight and looking like an NFL quarterback is another good step in the direction that he wants to go.

"He's just earning that trust of his teammates that he's going to need to do if he wants to be that starter. He impressed a lot of people out here tonight."

Josh McCown will start the 2015 season as the Browns' quarterback.