Michael Sam -- Ripped By NFL GMs, Agents, Scouts ... 'His Combine Was Flat Out Horrible'

Michael Sam's performance at this weekend's NFL veteran's combine may have been the final nail in his NFL coffin -- with multiple GMs, agents and scouts saying he wasn't just bad ... but "flat out horrible."

After Sam posted unimpressive numbers, including a slower 40-yard dash time than he posted at the 2014 rookie combine ... multiple high powered NFL sources tell us they believe there's no chance Sam makes an NFL roster this season.

As one big time NFL agent put it ... "My real honest opinion is that he was flat out horrible. He did not belong out there."

An NFL scout who was at the combine tells TMZ Sports he looked stiff and slow ... but says Sam's attitude was even worse. "He thinks he's a superstar. It would be nice if he could do something on the field to back up the attitude."

As for the NFL general managers ... one person says, "The concern was that he didn't look focused on the game. He regressed."

Another high powered NFL agent, who represents multiple Pro Bowlers, tells TMZ Sports ... "Here was a chance to show his determination and dedication and the GMs didn't see that."

"I think there's a chance he could play in the Canadian Football League. He sells tickets. He attracts fans. And from there you never know."