Glen "Big Baby" Davis isn't ready to give up on first-year head coach Joe Mazzulla just yet ... telling TMZ Sports if the Celtics are able to come back and beat the Heat and advance to the NBA Finals, he deserves to keep his job.
We got Davis out at LAX just hours before Game 5 of the Eastern Conference Finals tips off at the TD Garden in Boston ... and the NBA champ said Mazzulla's future with the team is contingent upon whether or not he can rally Boston from down 3-1 to beat Miami in the ECF.
"If you pull this off, you get to stay," Davis said. "If you don't, you're outta there buddy."
FYI -- no team has EVER been able to come back from trailing three games in NBA playoff history ... but after winning Game 4 on Tuesday, the Celtics are hanging on by a thread.
Davis also weighed in on why the Celtics have been inconsistent this season ... and he's pointing the finger at former head coach Ime Udoka, who was suspended by the team following an infidelity scandal last year.
"It f***ed the whole team up," Glen said. "They just had to go get another coach. It kind of f***ed 'em up a little bit."
Udoka, who was engaged to Nia Long, was suspended by the Celtics for the entire 2022-23 season ... even after the first-year head coach led the Cs to the NBA Finals against the Golden State Warriors.
Although Udoka is no longer with the team, Davis still views the 2-seeded Cs as a good team ... but said Boston's dynamic duo of Jayston Tatum and Jaylen Brown needs to play better.
"Jayson Tatum. Jaylen Brown. They better get that s*** in order, got dammit -- at least a good fight," Davis said. "We can come back. I truly believe. Miami hasn't been good all year. They haven't been consistent. They're playing well right now. We just gotta get on the same level."
Davis actually thinks it's possible Boston can be the first team to come back from down 3-0 ... saying he "truly believes" the Celtics have what it takes.