TMZ has learned ... one of the key players who made "American ldol" a success was so pissed last night after the show, he chewed out "A.I." producers backstage.

Rickey Minor -- who has been the bandleader for 6 seasons  -- is leaving A.I. to head up Jay Leno's band on "The Tonight Show."

Minor was fit to be tied after no one thanked him or wished him well -- hell, they didn't even acknowledge him during last night's finale.

Our "A.I." spies tell us ... when the show was over Minor went off on producers, angrily telling them how insulted he was by their silent dis.

Minor refused to go backstage for the champagne afterparty.  But producers pleaded with him and then got Randy Jackson to try and smooth it over with an unprepared speech.

Minor then said a few words but we're told, "You could cut the bitterness with a knife."

We're told Minor recanted and went to the afterparty -- but he was still fuming mad.

Simon Cowell wasn't the only one who bid sayonara to "American Idol" last night.

Dorian Holley -- the Vocal Coach and Associate Musical Director -- said farewell last night as well, and he's heading for "The Tonight Show."

Holley was also the Vocal Director for Michael Jackson and was a key player in the London tour that never happened. He was with Jackson hours before he died.

Holley will become the lead singer in "The Tonight Show" band. And he's not the only "A.I." musical guru who's jumping ship -- Rickey Minor will take over Jay's band.

Need a job? There are openings at "Idol."

Team Coco strikes again.



A Conan O'Brien fan posed for a photo with Jay Leno last night with the letters "Coco FTW" written on his hand -- which means "for the win."

Leno got the "Tonight Show" back and Conan got $32.5 million from NBC -- they're both winners.