#3 Willian
Chelsea have had some fine Brazilian players play for them and Willian was an amazing servant to the club. The forward gave some fine performances with Shakhtar Donetsk and Anzhi Makhachkala, before signing for the Blues in 2013.
Willian is a very hardworking player, to say the least. His ability to play in different positions in attack and at the same time help the defense with his high work rate was of massive help. He played an instrumental role in helping Chelsea win two Premier League titles.
Last season, the Brazilian decided to join Arsenal and was left with regrets once he came to know that his compatriot Thiago Silva was going to join the Blues. It only got worse when the Blues went on to win the UEFA Champions League earlier this summer. It is true Willian would not have enjoyed an extended future at Chelsea anyway. But the Blues were still willing to give him a one-year extension, which he refused to sign.
Willian mustered just a single goal in 37 appearances across competitions for Arsenal during his stay at the Emirates. He now plies his trade with Corinthians in Brazil. Safe to say, things did not go according to plan for the winger.
#2 Damien Duff
Damien Duff attracted the attention of many clubs with his performances at Blackburn Rovers. It was in 2003 that the Irishman earned a move to Chelsea to play under Claudio Ranieri.
Unfortunately, the Italian manager was soon sacked and on came Jose Mourinho. Duff initially struggled to get regular game time but once he was given the chance by the Portuguese manager, he became a regular in the starting eleven. With Arjen Robben on one wing and Duff on the other, Chelsea were brutal in attack, winning back-to-back Premier League titles. The winger had this to say about his departure:
"I cried on the day that I left [Chelsea] – looking back, that probably should have told me I was making the wrong call, as I never cried when I left Blackburn, Newcastle or Fulham, or even when I retired. But it was my own decision."
In 2006, the Irish forward decided to join Newcastle United after achieving success with the Blues. Duff later accepted that it was the wrong call as his career did not flourish as much as it would have by staying at Chelsea.
#1 Eden Hazard
Like many other players, even Eden Hazard was a target for some of the top European clubs when he played for Lille. It was between Manchester United and Chelsea that the Belgian had to decide.
He eventually joined the Blues in 2012 in order to enhance his development and career. With his nimble footwork, smart dribbling and amazing ability to run past defenders, Hazard was a spectacular player in the Premier League. He won two league titles at Chelsea, with his best season coming in 2018-19, where he scored 16 goals and recorded 15 assists.
The following season the Belgian forward joined Real Madrid. Despite winning La Liga in his first season with Los Blancos, Hazard has had a torrid time with the Spanish giants.
He's yet to reach his best form with them and is struggling to perform consistently due to recurring injuries. Meanwhile, Chelsea have gone on to win the UEFA Champions League. Without the shadow of a doubt, Hazard regrets leaving Stamford Bridge.