Michael Sam Was No Jackie Robinson ... But Gay Athletes Still Owe Him

Michael Sam should be hailed as a hero in the gay community ... even though his football career is in the crapper -- so says activist Esera Tuaolo, the first NFL player to come out after retirement.

TMZ Sports spoke with Tuaolo ... who back in 2002 shocked the sports world by announcing he'd been in the closet during his 9 years playing with the Falcons, Packers and Vikings.

Sam's catching a lot of flak since quitting the CFL -- but Tuaolo says he should get credit for coming out at the most crucial time in his career. He says, "It was definitely awesome, helped kids and I think will make it easier for more people" in the future.

He acknowledges Sam fell short of being a Jackie Robinson type, but adds very few have that kind of drive ... "Jackie was incredible, he didn't give a crap about anything else. He knew he had a gift."

Tuaolo says he tried to contact Sam, but never heard back. Had they spoken, he would have warned him, "If you're going to be THE ONE, you have an obligation to stay focused on the goal."

As for Sam making a comeback ... Tuaolo says he's young enough to do it, if he puts his mind to it.