'%20x='0'%20y='0'%20height='100%25'%20width='100%25'%20%0A%20%20%20%20%20%20%20%20%20%20xlink%3Ahref='data:image/jpg;base64,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'%3E%3C/image%3E%3C/svg%3E)
#3 Diego Costa
Diego Costa's departure from Chelsea was a baffling one, considering he was a key part of the Chelsea team during his time at the club.
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Costa was signed by Chelsea from Atletico Madrid in the summer of 2014, and he lit up the fireworks during his debut season at the club. His fierce determination would represent the spirit of Jose Mourinho's Chelsea side. Costa netted 20 goals across the league campaign as the Chelsea faithful saw one of their most convincing title wins.
Like most of Chelsea's squad, Costa's form dipped during the following season, leading to Mourinho's sacking. The Spaniard would once again however hit 20 league goals under Antonio Conte in 2016-17, firing Chelsea to another Premier League title.
However, a rift with the manager saw Costa receiving a text message from Conte saying his services were no longer required at the club. As such, the Spaniard returned to Atletico Madrid the following season.
Costa is arguably the best striker Chelsea have had since Didier Drogba, with big-money signings like Fernando Torres and Alvaro Morata failing at the club. The Blues have re-signed Romelu Lukaku for a club-record £97.5 million this summer. It remains to be seen whether the Belgian will find success at Stamford Bridge or not.
Chelsea fans, meanwhile, would have definitely been annoyed with the way Costa departed the club.
#2 Mohamed Salah
Mohamed Salah was certainly not known by many when Chelsea signed him for a fairly hefty £14.5 million in January 2014.
Known for his pace on the wings, Salah's career never kicked off at Chelsea. Apart from scoring in the 6-0 win over Arsenal and featuring in the infamous "Gerard slip" match against Liverpool at Anfield, Salah barely enjoyed any big moments.
Two successful loan spells with Fiorentina and Roma eventually led to Chelsea selling Salah to the latter for around £14 million in 2016. 20 goals in just over 40 appearances in the 2016-17 season led to Jurgen Klopp and Liverpool paying £30 million pounds for his services.
With 132 goals and 50 assists in 212 appearances, one Premier League title, one Champions League title and two Premier League Golden Boots, Salah has been nothing short of sensational.
It speaks volumes about the success that Salah and Liverpool have enjoyed. He is considered one of the very best in football right now and is constantly spoken about in the same bracket as Lionel Messi and Cristiano Ronaldo.
Chelsea have not finished above Liverpool in the league since Salah's arrival at Anfield. This is a transfer mistake that will certainly hurt the Blues fans in the years to come.
#1 Kevin De Bruyne
Perhaps the biggest regret Chelsea will have is letting go of Kevin De Bruyne, who has arguably turned out to be one of the best midfielders in the world right now.
Signed from Genk in 2012 for a rumored £7 million pounds, De Bruyne's two-year stay in London coincided with what was perhaps the club's best ever time for attacking midfielders. The club had the likes of Willian, Oscar, Eden Hazard and even Juan Mata during that time, making it clear that De Bruyne would be down the pecking order.
As such, De Bruyne was allowed to leave on loan to Werder Bremen, where he impressed everyone with his performances. Many fans hoped the Belgian would repeat that at Stamford Bridge.
For whatever reason though, De Bruyne struggled under Jose Mourinho and within six months he was sent back to Germany, but this time it was a permanent move to Wolfsburg.
In his 18 months there, De Bruyne showed his true class and even bagged Germany's Footballer of the Year award in 2014-15. This convinced Manchester City to sign him for £55 million in the summer of 2015.
Since then, De Bruyne has established himself as one of the most acclaimed and accomplished players in the world. His creativity, vision and eye for goal has made many people consider him the best attacking midfielder in the world right now. His trophy cabinet at City consists of three Premier League titles, one FA Cup and five League Cups.
Chelsea have lacked a player of De Bruyne's creativity and ingenuity in the middle of the park in recent years. One could only imagine what the Blues would have achieved had he still been at the club.
