We have often seen players struggle to fulfill their potential at one club before exploding at another, leaving the previous employers in tears because of what could have been. The club owners and managers usually don’t have enough patience for new players and they tend to sell them after one poor season, but they sometimes live to regret it. The club officials that were in charge of these transfers probably still have problems sleeping at night.
7.) Gerard Pique (Manchester United to Barcelona)
Gerard Pique started his career at Barcelona’s famous youth school La Macia, but before signing a professional contract at Camp Nou, he decided to join Manchester United. After featuring in just 12 league games during the four years at Old Trafford, Sir Alex Ferguson opted to sell him back to Barcelona for the fee of €5 million. Pique soon became a key player for both Barca and Spain national team, leaving Sir Alex Ferguson to regret the fact he hadn’t given him a real chance at Old Trafford.
6.) Diego Forlan (Manchester United to Villarreal)
Forlan arrived to Old Trafford for a fee of £6.9 million amidst high expectations, but after scoring just 17 goals in 95 appearances, the Uruguayan was shipped to Villarreal for mere £3 million. In his first season at El Madrigal Forlan won the Pichichi Trophy by scoring 25 league goals, while he even reached Champions League semi-final with the Yellow Submarine the next season. Villarreal made nice profit on the striker, selling him for €21 million, while Forlan managed to achieve the ultimate feat, having won the 2010 World Cup Best Player Award.
5.) Kevin Keegan (Scunthorpe to Liverpool)
When Bill Shankly brought Kevin Keegan for £35,000 from Scunthorpe, he thought he was signing an average midfielder, but he instead got an excellent goalscorer who helped the Reds reach unimagined heights during the ‘70s. After scoring exactly 100 goals, Keegan left for Hamburg, with Liverpool earning £500,000 from the deal. Keegan also amassed 63 England caps and was considered the first real superstar in English football.
4.) Nicolas Anelka (PSG to Arsenal)
Nicolas Anelka arrived to Highbury from PSG in one of the trademark Arsene Wenger deals, with Arsenal paying just £500,000 for the then 17-year-old striker. After helping the Gunners win the Premiership and FA Cup titles in his first season as a first team regular, Anelka, just like Arsenal, had a slow second season and quickly became unsettled at Highbury. Real soon came calling and splashed out £22.3 million for the Frenchman.
3.) Andrea Pirlo (Inter to Milan)
Andrea Pirlo was seen as one of the hottest prospects in Italy when Inter snatched him from Brescia, but the midfielder failed to prove his potential at Giuseppe Meazza and was sold to Milan a couple of years later in a transfer that involved quite a few players from both camps. Pirlo went on to become an integral part of the Rossoneri team that won numerous trophies in the next few years, while enjoying a lot of success with Italy national team as well.
2.) Cesc Fabregas (Barcelona to Arsenal)

At a moment when Barcelona are pondering a bid of €60 million for the player that was once in their own youth academy, Barca fans have every right to be aggrieved with the club management for allowing Cesc Fabregas to leave for Arsenal completely free of charge. The Spain international joined Arsenal when he was just 16 but quickly became one of the best midfielders in the world despite his fragile age. He has, however, never forgotten Barcelona, with the whole of Catalonia now hoping he would soon return to Camp Nou.
1.) Eric Cantona (Leeds United to Manchester United)
Leeds United signed Eric Cantona from Nimes for £900,000 with the Frenchman proving an instant success as he helped the Whites win the final Football League First Division title, before the competition made way for the Premier League as we know it. Everybody was surprised when club chairman Bill Fotherby sold Cantona to Manchester United for just £1.2 million, and that proved to be one of the worst decisions in professional football as the Frenchman developed into a real star at Old Trafford before retiring from football five years after leaving Leeds.