These moves evoked much 'shock and awe' but for all the wrong reasons.

Bill Shankly once famously said, “At a football club, there's a holy trinity - players, managers and the supporters.” Of these three pillars of the game, supporters play the most crucial role. They are the ones who bring passion to the game and give their all, emotionally and mentally. 

As fans, we love the circus that surrounds the transfer window; unless, of course, it is to the marring of our beloved football clubs. Although most transfers result in an amicable agreement, some negotiations turn vitriolic. A war of words often dominates newspaper headlines as teams try to cling on to their best players. Some clubs resort to irrational tactics to get the player they want, sometimes a player believes the grass is greener on the other side.

Players like Francesco Totti, Steven Gerrard and Ryan Giggs are the epitome of loyalty in football. It is heartening for the fans to see a local lad play for their beloved club. But, as history suggests, for every Paul Scholes there has been a Robin van Persie.

Also read The fall of an ERA: Barcelona

However, every so often comes a transfer that no-one expected. A bolt from the blue: a player crossing the divide between two bitter rivals, or stepping up or down several levels above or below where they should be. These usually result in some fun and games afterwards. 

Such transfers have caused outrage and have forever brought them in the previous club fans' bad books. We bring you the most controversial transfers for every position since the dawn of this millennium.

Goal Keeper

Iker Casillas 

Iker's Casillias' transfer to FC Porto was rather sleek but was surrounded by aggressive posturing against his former club Real Madrid. He progressed up through the ranks at Los Blancos and played for the first-team for a good 16 years, winning 19 major titles including three Champions League titles. After the dismal trophyless season of 2014-15, Club President Florentino Perez was desperate to make amends. His axe went straight to the captain's and manager's head. He released Casillias of his contract and sacked Carlo Ancelotti.

Emotions got the better of Casillias as he wept during the press release of his departure

The consequences of the President's fury were disastrous. Casillas cried while leaving the club in an interview and refused the opportunity to have his testimonial. He struggled for a good amount of time in Portugal but regained his form by keeping most clean sheets in the league with FCP since arriving. Many deemed him to be past his best after his acrimonious switch but he's improvised like fine wine. He stands tall in the league of the old stalwarts of football who have not declined with the likes of Gianluigi Buffon, Zlatan Ibrahimovic and many more.

Defense

Thiago Silva

The Brazilian defender, along with Zlatan Ibrahimovic, was publically criticised by football pundits and managers for switching to a rather easy league. Zlatan was comparatively spared but Silva was money shamed by the AC Milan faithful. Amidst his transfer speculations, Milan had secured his signatures for a 5-year deal, only to be sold after just 12 days. He went to Paris for €42 million, making him the costliest defender at that time.

Moving to a league in its pre mature stage, many believed that the then 27-year-old defender's decision was not wise to take in his prime. Silva went on to win 16 domestic trophies in France and shutting his critics once and for all.

Leonardo Bonucci

Leonardo Bonucci, the de facto best defender in the world, was sold to AC Milan this summer. Juventus' rivals for £35m. The fact that Juventus chose to sell to their emerging rivals, no matter what the fee, is in itself unbelievable. One of the prime reasons for this move, according to some reports, is his apparent rift with manager Massimilano Allegri and Bonucci did little to deny those rumours. 

Leonardo Bonucci and Dani Alves had a stern rift with their former Juventus manager which saw them leave the Old Lady

Braced for a hostile reception when Milan visit Juventus later this season, Bonucci is supposed to lead the Rossoneri. He played a key role in the Bianconeri winning six successive Serie A titles and established himself as arguably the best centre-back in the world along the way. Bonucci excels at regaining possession for his side without having to go to ground, while his reading of the game allows him to snuff out danger often before it happens.

Sol Campbell

Sol Campbell is one of the greatest players to have ever worn a Tottenham jersey, but his success at White Hart Lane was limited. Despite playing for the club for close to a decade, Spurs never finished higher than seventh in the Premier League, denying the centre back the opportunity to play Champions League football.

Despite Tottenham offering him a deal to become their highest paid player ever and months of public assurances that he would not leave or play for their bitter rivals, he nevertheless signed for Arsenal.

It was a surprise for the fans and reporters as well to see Campbell signing for Tottenham's eternal rivals. Adding insult to injury, the centre-back went on to win two league titles and three FA Cups during his time with the Gunners. Spurs loyalists labelled him 'Judas' for his unthinkable move (from a fan's perspective), with the tag expected to follow him forever.

Ashley Cole  Few transfer sagas have left behind as sour a taste as Ashley Cole’s eventual 2006 move to Chelsea. Having played for his childhood club, Arsenal, for six years, Cole met with Chelsea representatives, including manager José Mourinho, without informing his owners. The meeting infringed league rules and Chelsea, Cole and Mourinho were all heavily fined.

He earned the title of - 'Cashley' from the Arsenal fans, thanks to his money-minded move to the Blues. Cole later revealed that he felt like Arsenal were "feeding him to the sharks" as he was frustrated with the Gunners' resistance to offering him an improved deal. Till date, Arsenal fans hold a grudge against a player who once was one of their own. 

Midfield

David Beckham

After the Treble triumph, it was believed that Sir Alex would never sell his precious Fledglings but once David Beckham seemed to lose his focus on the game, the €35 million deal from Manchester United to Real Madrid seemed inevitable. Everything started when Sir Alex had to shave down Becks' ridiculous hairdo before their visit to South African Hero, Nelson Mandela.

The rift continued when David was accused of lacking the spirit and drive to give his fullest for the club, followed by the infamous locker room boot spat between the duo. Rest assured, Sir Alex was adamant of letting go David because of his beliefs of being greater than the team or the club itself. The love for the team, the fans and the club was never lost. Sir Alex and David are reported to have moved on from their past but David admits of not having watched any of the single games of United for several years after his departure.

Also read Dissecting Manchester United's journey in the post-Sir Alex Ferguson era!

John Obi Mikel

John Obi Mikel's arrival in the Premier League was marred by a huge controversy among two English heavyweights. It came to light that Manchester United had pressurised the then 18-year-old Mikel to sign a 4-year contract in the absence of his agent which would have seen him join the club in 2006. It was later discovered that Mikel had signed multiple deals with various sports agents in England. 

Mikel's press conferences were a regular affair and gathered much attention on him

After United’s advances, Chelsea then complained to FIFA that talks were held between Mourinho and the player, which were denied by Norwegian side Lyn. Then in a bizarre turn of events, Mikel held a press conference wearing a Manchester United shirt and stated that he had signed a contract with the Red Devils.

This resulted in threats from unknown sources to the player. His parent club, Lyn and United claimed that Mikel was kidnapped by either Chelsea or by the media. After nine days of his disappearance, Mikel and his agent miraculously appeared in London and revealed that he was forced to sign a contract with United and that his heart was set on joining Chelsea.

Cesc Fabregas

One of the rare players to have boo boys follow him to two transfers is none other than Cesc Fabregas. Over the years, he has earned many things including the hate of Blaugranas and Gooners. After impressing Arsene Wenger during his time at La Masia, he was transferred to Arsenal for a negligible fee of €3.2m at the age of 16. While progressing through the ranks at Arsenal, he became a regular at Emirates Stadium only to be sold back to Barcelona after a serious bust-up with Wenger.

In fact, when Spain won the 2010 World Cup in South Africa, fellow Spanish players put a Barca shirt over him while he was still an Arsenal player. The saga continued until the next summer and resulted in a move to Barcelona, an year later.

Fabregas adorning Barcelona colours in the heat of celebrations did not go down well with the Arsenal faithful

After winning six major trophies at Camp Nou, he surprised everyone with a transfer request. He went to Stamford Bridge following an approach from Mourinho, one of the most hated men in the Catalan capital. His switch reignited the rivalry between the Gooners and the Blues.

Angel Di Maria

Angel Di Maria's life turned around after winning the Champions League with Real in 2013/14 and just before the World Cup he was deemed to be the next big thing. But, what came afterwards was sheer fate. James Rodriguez rose to prominence at the event in Brazil and made himself an object of Perez's obsession. The Madrid President signed him and was willing to let go of Di Maria, Man of the Match in the previous season's UCL final. 

United signed him for a then British record transfer fee of £59.7m but it failed to work out with Louis van Gaal at the helm. His drip in form and poor performances enraged the United faithful who then, on various occasions, were reported to have thrown pebbles and gravels into his Manchester residence. Fearing for his family's safety, he missed the pre-season tour of 2015 and signed for Paris Saint Germain in Van Gaal's absence. He is regarded as a 'coward' and a 'snake' by a section of United's faithful.

Strikers

Robin van Persie

The Dutchman was a fan favourite, captain and a striker who single-handedly carried his team on many occasions. Arsenal fans loved Robin van Persie and he loved them back. It was understood Arsenal were willing to make Van Persie their highest paid player ever, but never actually offered him a new contract. Juventus and Manchester City also bid for the striker, but it was reported that of the three, United were the only side Van Persie would have considered joining.

After the turn of the decade, the two sides were locked in many title fights. Hence when the Dutchman moved to the Theatre of Dreams, Arsenal supporters felt betrayed and termed him a 'traitor' and a 'mercenary.' Arsenal fans’ argument was that the club had stood behind the player during his injury problems but when the club needed its best player to stand with them, he left for greener pastures.

After being bashed by the Gooners' fans, Van Persie showed no mercy while hosting his former club

Tensions rose further when Van Persie celebrated after scoring a goal against Arsenal at Old Trafford after being fed up of the hostile reception by the Gunners fans. Van Persie won United their 20th league title during his first season at the club, much to the frustration of Arsenal fans.

Luis Figo

The legendary Portuguese winger had the adoration and cheers of the Barcelona fans for five years, winning every major honour at the club except the Champions League. The scorching hot rivalry between Barcelona and Real Madrid, perhaps the greatest in world football, needed no further stoking. Those flames were fanned to unprecedented levels though when Luís Figo completed a shock move to the Bernabeu in 2000, for a then world record fee of £37m. 

Abuse faced by Portuguese legend Figo was at an all-time high during his return to Camp Nou

Two years later, during a game at Camp Nou, Figo was subject to the Barcelona fans' ire as the raucous home crowd brought the game to a halt for 12 minutes. Along with bottles, coins and lighters, a pig's head was also thrown near the corner flag as the playmaker was preparing to take a corner, 'Traitor' and 'scum' signboards adorned the stadium, effigies were burnt in the crowd (close to where Figo was standing) which reflected the anger that the Catalans had in their hearts about this controversial transfer.

Most controversial- Transferred XI © The Corner-Sourav Bose

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This hatred among the Barcelona fanbase makes his move to the Bernabeu, one of the most controversial transfers of all time. Before him, 17 players had been transferred to Real Madrid from Barcelona but none of them met such a ferocious reaction from the Barcelona supporters.