Johnny Damon is going to bat for fired Red Sox exec Dave Dombrowski ... telling TMZ Sports, "Dombrowski is a very good GM, very honest."
Boston made the shocking move just a few days ago to can their team's president of baseball operations -- just 10 months after he won the World Series.
Reporters out in Beantown are perplexed by the move ... and nobody seems to have a definitive answer as to why the dude was fired after having so much success since he was hired in 2015.
When we got Damon out in NYC on Wednesday ... he said of the surprising move, "[The Red Sox] must know something else that's going on."
But, Damon ain't concerned that this will be a death blow for Dombrowski ... he played for the guy in Detroit in 2010 -- and says Dave's a really good GM.
"If he wants another job, he'll find another job," Damon says ... "I hope for him the best."
As for what he thinks ultimately went wrong in Boston -- Damon seems to think bullpen issues cost Dave his job, saying, "He wasn't given a closer this year and their setup guy was a headache."
Maybe they should've given Craig Kimbrel that big deal after all, huh???