9:55 AM PT -- The Mets have confirmed Feliciano's death ... saying in a statement the org. is "so saddened to hear of the loss to their family today."
"Pedro Feliciano will be remembered as a beloved member of the Mets organization for his impact as a great teammate as well as his reputation as one of the most competitive, durable and reliable relievers during his time in Queens," the Mets added.
"Our thoughts and prayers are with the entire Feliciano family. Rest in peace, Pedro."
Ex-MLB player Pedro Feliciano -- who pitched for the New York Mets for 9 seasons -- died on Sunday night, baseball analyst Eduardo Perez reported.
He was just 45 years old.
Perez did not reveal a cause of death for Feliciano ... but the ESPN broadcaster did say the former reliever passed away in his sleep.
Just found out that former #Mets reliever Pedro Feliciano passed away last night in his sleep. He was 45years young. He was a really good released but a better person off the field. He will be missed 🇵🇷 #Leones#Cangrejeros. He was jet skiing yesterday with his family. #sad 😟
Feliciano revealed in '13 he had been diagnosed with a rare medical condition -- one in which he said doctors found he had a "little hole" in his heart. It's unclear if that played any role in his death Sunday.