9. Appointing Andre Villas-Boas
In June 2011, Chelsea announced former Porto boss Andre Villas-Boas would succeed the recently sacked Carlo Ancelotti at the helm of the club, a decision which came as quite a surprise to many observers. At just 33, the Portuguese national lacked experience having only managed Académica prior to his stint at the Estádio do Dragão. Granted, there he did win practically everything he could have, including the Europa League, but that still did not prevent a few eyebrows being raised over Abramovich's decision to appoint him, especially considering he paid £14 million to trigger his release clause to bring him to Stamford Bridge in the first place. Another costly mistake, as it turns out. Villas-Boas lasted a mere nine months in charge before he joined a long line of former Chelsea managers in being handed his P45.