Sean Burroughs -- the ninth-overall pick in the 1998 MLB Draft -- died from a fentanyl overdose.
The late MLB player's official cause of death is listed as fentanyl intoxication and his death has been ruled an accident ... according to the Los Angeles County Coroner.
As we reported ... 43-year-old Sean died back in May, when he was found unresponsive next to his car in a Long Beach parking lot outside his son's Little League baseball game.