The Spice Girls/Cardigans thing was him, but Jason Priestley began to EP in Season 8, I believe. He brought in Michael Braverman to try to make the show a more grounded drama. It didn't work, Braverman was tossed and JP fled the show in a very strange way at the beginning of Season 9 after an equally strange Season 8 finale. To each their own taste of course, but I remember Season 8 being dismally boring, and the longtime creative personnel were not happy with it either and have sounded off about it.
Season 7 is a huge dud on many levels and completely forgettable despite the sad exit of Clare (Kathleen Robertson was focused on her movie work with Gregg Araki). But Season 8 just never worked for me on any level either. The only thing that did was Hilary Swank, and they dumped her halfway through the year very unceremoniously while trying to retool the show. She then went on to become a movie star in record time. Vincent Young was hired just because he was a very buzzy hunk in a big Coke commercial or something at the time, I can't remember exactly what, but they tried to push him as the new heartthrob and pair him with Donna to push her as the sexy lead, and they were both just dismal together. And once that ended and Dylan came back he had no purpose but hung around for another year or two with third-tier story. It was all just wretched to me. YMMV. The last year I bothered with in full was Season 6 - like Season 4 of Melrose it got campy and OTT, but unlike Melrose its characters weren't as adaptable for the changes. But it still had some good stories and great new characters like Emma Caulfield's Susan Keats. After Season 6 the show is a wash to me.