Complex sentence: On 10 November 2011, he was appointed the manager of Portsmouth, and just under a year later he became manager of Blackpool, but after just 3 months he quit the Seasiders to become manager of Blackburn Rovers.
Split into simpler sentences: On 10 November 2011, he was appointed the manager of Portsmouth, and just under a year later he became manager of Blackpool. After just over two months as Blackpool manager he quit the Seasiders to become manager of Blackburn Rovers.