Quincy Jones sat down to talk with David Marchese at Vulture, and it’s … interesting:

That they were the worst musicians in the world. They were no-playing motherfuckers. Paul was the worst bass player I ever heard. And Ringo? Don’t even talk about it. I remember once we were in the studio with George Martin, and Ringo had taken three hours for a four-bar thing he was trying to fix on a song. He couldn’t get it. We said, “Mate, why don’t you get some lager and lime, some shepherd’s pie, and take an hour-and-a-half and relax a little bit.” So he did, and we called Ronnie Verrell, a jazz drummer. Ronnie came in for 15 minutes and tore it up. Ringo comes back and says, “George, can you play it back for me one more time?” So George did, and Ringo says, “That didn’t sound so bad.” And I said, “Yeah, motherfucker because it ain’t you.” Great guy, though.

And:

Musical principles exist, man. Musicians today can’t go all the way with the music because they haven’t done their homework with the left brain. Music is emotion and science. You don’t have to practice emotion because that comes naturally. Technique is different. If you can’t get your finger between three and four and seven and eight on a piano, you can’t play. You can only get so far without technique. People limit themselves musically, man. Do these musicians know tango? Macumba? Yoruba music? Samba? Bossa nova? Salsa? Cha-cha?