With rumors swirling on Brady potentially not playing this season, we asked Deebo himself -- Tom's teammate last year -- and he told us it would NOT surprise him ... given the sacrifices TB, Gisele and the kids make so he can play ball.

“That’s up to Tom and what decisions he and his family make as far as what he wants to do, and if he does want to continue to play, what he’s willing to sacrifice and the family is willing to sacrifice,” Harrison told TMZ Sports.

James would know -- telling us that's why he decided to retire earlier this week.

Specifically, the Pro Bowl LB says he's interested in introducing his 2 sons to tackle football -- and possibly even coaching them!

Deebo says it's a tough decision for any parent to make given everything that's out on CTE -- but explained why he wants his sons exposed to it before they hit their teens.

"Everything in life has dangers ... I'm not gonna live in fear of things that could possibly happen."