"You work your ass off," the former Pats superstar says. "In that system, in that organization, you work hard. And, there's a lot of pressure put on you."

Don't get it twisted ... Willie says that's why the Patriots are so damn good -- they treat every player the same way and expect results all across the board.

But, the Pats legend tells us that can be taxing ... and he gets why Brady and Gronk wanted to see a fresh perspective down in Tampa Bay at the end of their Hall of Fame careers.

"It's a tough atmosphere because there's a lot of pressure on winning," Willie says. "Everybody is held accountable."

As far as any animosity between Bill Belichick and his former superstars over the way things ended ... Willie says there's no hate there, telling us the guys still have a ton of respect for each other.

"What they did in New England together, as a duo -- as a trio," McGinest says, "will never be duplicated ever in football history again."

Willie tells us he expects Gronk and Brady to be at Patriots reunions as soon as their careers are over ... and even says ceremonial retirements in New England for both dudes are on the table.