Rea have now managed only one win in their last seven matches, sit ninth in La Liga and earlier this month went more than eight hours without a goal.
From his personality to his difference of opinion in transfers, here we look at three reasons the Italian only lasted two seasons with the Blues.
Conte leaves with the best win percentage 65.1% of any of Chelsea's managers in the Premier League era.
Seri was swayed by the promise of regular first-team football and Chelsea's case was not helped by being still in a state of flux over the status of manager Antonio Conte.
The polish on Conte's tenure at Chelsea has become tarnished both at boardroom level and amongst his players.
England assistant manager Steve Holland says Gareth Southgate qualities echo Jose Mourinho, Antonio Conte
Steve Holland worked with the London club's first team from 2011 before joining Gareth Southgate, and England, in 2016.
Conte is said to have infuriated several Chelsea stars with his intense personality and regimented training sessions.
The 59-year-old former banker has been linked with Chelsea to replace fellow Italian Antonio Conte whose future at the English Premier League club remains uncertain.
To avoid the unpleasant prospect of watching Mourinho celebrating at his expense, Antonio Conte needs to find a way to unify his team following last weekend's shambolic 3-0 loss at Newcastle.
Manchester United vs Chelsea: Stakes raised for Jose Mourinho-Antonio Conte feud in FA Cup final showdown
Mourinho and Conte renew hostilities with the stakes heightened when Manchester United and Chelsea face off in FA Cup final.