What does Paul say on Anthology about it? That they were good before Ringo, but when he joined something just happened? I don't remember, but I think he was right. There was something about the chemistry the four of them had. I wouldn't put down Ring's contributions. Just because he wasn't a great songwriter doesn't mean he didn't bring something important to the band. And if it wasn't for him, their movies wouldn't have been half as funny!