That's not Mandy Moore, she is hot though
I always had a thing for Shannen Doherty.
The whole story of the fall of "Brenda Walsh" is a fascinating episode in the convergence between entertainment and the Internet. You see, "Beverly Hills, 90210" was the first TV series in which the fans, via the Internet, were a real pressure group. Now, we take it for granted but then it was the very first. And the fan base was passionately loyal, almost obsessed.
Shannen didn't realize that the rules had changed. She alienated the fans. They turned against her online. It got as vicious as, practically, an online gang rape. Rumors of discord between Shannen and practically every other cast member reached such a volume that there was no sense denying it.
The death rattle is when the writers start taking sides in backstage quarrels. On her final season, her earlier role of moral center long gone, her character was erratic, moody, going to extremes, alienated from the main plot lines, a general pain in the butt.