#3 Andriy Shevchenko to Chelsea
Andriy Shevchenko was one of the most lethal forwards the game has ever seen, especially during his time at AC Milan, where he won the Champions League trophy and the 2004 Ballon d'Or award.
Shevchenko is Ukraine's all-time leading goalscorer, and also led the goalscoring charts in three Champions League editions. The prolific forward made the move to London in the summer of 2006 amid huge expectations from the Chelsea faithful. It was a statement signing of sorts, as Chelsea announced to the footballing world that they could attract the biggest names in the game.
Shevchenko was a favourite of Roman Abramovich, who arrived at Stamford Bridge with a burgeoning reputation, but things didn't exactly go to plan for the Ukrainian. His stint in the Premier League lasted only three years, one of which was spent on loan at AC Milan.
Chelsea's style of play didn't really suit Shevchenko, and he never really adapted to the demands of English football. In 77 appearances for the Blues, the former Ukraine manager could find the back of the net 22 times.
In contrast, Shevchenko was directly involved in 220 goals (175 goals and 45 assists) in 322 appearances for Milan.
#2 Cristiano Ronaldo to Juventus
Portuguese megastar Cristiano Ronaldo shocked the footballing world when he chose to leave Real Madrid after nine trophy-laden years at the club.
Juventus announced the signing of Ronaldo in the summer of 2018, and the Portuguese hit the ground running almost immediately. In his first season at the club, Ronaldo racked up 28 goals and 11 assists in 43 appearances. He bettered his goalscoring haul the next season, finding the back of the net 37 times in 46 appearances.
Ronaldo has already registered over 100 goals for Juventus in three years at the club, becoming the first player to score 50+ goals in three of Europe's top leagues - Serie A, La Liga and Premier League.
For the other Ballon d'Or winners on our list, their move did not work out because they didn't adapt to a new country or fell out of form. In Ronaldo's case, the team around him was an ageing unit, and became a shadow of the world-class squad it once was. Some of Juventus' best players last season, including Alvaro Morata and Federico Chiesa, are on loan from Atletico Madrid and Fiorentina, respectively.
Perhaps it would have made more sense for the now-36-year-old to spend some of his last years in professional football with the more promising squads of PSG, Manchester City, Chelsea or Manchester United, to name a few.
#1 Kaka to Real Madrid
Much like Shevchenko, the Brazilian sensation Kaka could not adapt to Jose Mourinho's defensive and counter-attacking playing style.
Both Shevchenko and Kaka were players who liked time on the ball, and had the extraordinary ability to make things happen with the ball at their feet. Mourinho set up defensively well-drilled and well-oiled teams at Real Madrid, which failed to fully utilise the talents of the Brazilian magician.
Kaka showcased some of his best football during his six-year spell at AC Milan. The Brazilian was at his peak in the late 2000s, propelling the Rossoneri to Champions League glory in 2006-07 and taking home the Ballon d'Or award at the end of the year.
Kaka was the top scorer in AC Milan's glorious Champions League campaign that year; he also won the Serie A, Supercoppa Italiana, FIFA Club World Cup and the UEFA SuperCup.
However, the now 39-year old failed to recreate something similar in the Spanish capital. Kaka struggled with injury and fitness for most parts of his Madrid career, registering only 120 appearances in over four years at the club.
In retrospect, Kaka would have been better off continuing at AC Milan, as the Rossoneri's style of play suited him far more than Mourinho's defensive approach.