Diego Simeone can firmly take the credit for Costa earning his European recognition prior to his move to Stamford Bridge two summers’ ago. It was the Brazil-born striker’s 27 goals in the 2013-14 season that fired Atleti to their first La Liga title in 18 years. Simeone warmly wished Costa well after his transfer to Chelsea was agreed, and it could be such affection that the centre-forward needs to rediscover his scoring boots. The Argentine appears to maintain effective relationships with his former players – take Filipe Luis as an example – which should be a key quality needed if Chelsea begin their search for a manager capable of staying in the job for the long-term.