The transfer market is where a club goes to for repairing its team. Football clubs for the past few years have been spending an astronomical amount of money on players who they think will be their catalyst for success.
However, playing smartly in the transfer market is more important than just spending a lot of money on whoever is available. The history of the football transfer window is filled with bargains and smart buys, which have greatly helped the clubs grow. During the past few seasons, Juventus and Liverpool are prime examples of this strategy to buy cheap and smart, rather than to splash the cash.
Also read - 10 best deadline day signings in PL history
In this list, we take a look at players who were allowed to leave their club for free and then succeeded in their next club. Some of the smartest pieces of business in football are listed here -
#5 James Milner - Liverpool
To be fair, Manchester City were not entirely wrong in letting James Milner go in 2015. The midfielder was 29 at the time and the Cityzens had the cash to spend on more creative players who they thought would replace Milner. However, the club never anticipated the success which the English midfielder would have at Liverpool.
In 2015, Liverpool were not a force to be reckoned with - and then Jurgen Klopp happened. Fast forward four years later, and the former Leeds United player is now the vice-captain of the European champions. Milner won the Premier League twice with Manchester City, but now he has two European trophies with Liverpool, which is two more than his former club have.
The English international has been a consummate professional for the Reds, fitting in wherever required. A versatile player who inspires his teammates with his work ethic, James Milner is one of the better free transfers of this era.
#4 Sol Campbell - Arsenal
Sol Campbell is one of the most famous players in North London, due to the fact that he made a switch from Tottenham Hotspur to Arsenal in 2001. Spurs fan labelled him a Judas and to this day he receives abuse from some of them. However, with the success that the striker achieved with Arsenal, he could not care less.
Arsene Wenger loved Campbell as a defender, and the former England international repaid that faith in kind. The centre-back was an integral part of the team which made history as they went an entire Premier League season unbeaten in 2003-04. Apart from this, Campbell won the FA Cup twice and the Premier League once more, and established himself as one of the best defenders in England.
Campbell's move across these two rivals is still one of the most shocking transfers in Premier League history, and it must sting Spurs fan to see the trophies which their former player won with the Gunners.
#3 Paul Pogba - Juventus
Paul Pogba has not lived up to the lofty expectations that preceded him when he re-signed for Manchester United a few years ago - however, no one can debate the impact the midfielder had in Italy.
The French midfielder came through the ranks of Manchester United, ut was unhappy with the lack of playing time and opportunities at Old Trafford. In 2012, then manager Sir Alex Ferguson confirmed that Pogba had left England for Juventus. Although adamant about his decision to let him go, maybe Ferguson did regret his choice a few years down the line.
Pogba shone with his new team. The World Cup winner made 178 appearances for the club, scoring 34 times and assisting 43 goals. He won the Serie A four times and managed to reach the Champions League final in 2015 - all by the age of 23. If that was not enough, the money which Juventus made off of Pogba's return to Manchester United speaks volumes - an £89 million return on a zero investment.
Pogba is easily one of the greatest free transfers of all time.
#2 Andrea Pirlo - Juventus
"When Andrea told me that he was joining us, the first thing I thought was: "God exists". A player of his level and ability, not to mention that he was free, I think it was the signing of the century!
- Gianluigi Buffon on Pirlo's transfer to Juventus in 2011
To this day, it still baffles the mind to think that AC Milan let Andrea Pirlo go to Juventus on a free transfer. Juventus are the masters of getting the best free agents on the planet, but Pirlo might just be their jewel in the crown.
Having spent a decade with AC Milan, Pirlo left the club in 2011 and joined direct rivals Juventus in Turin. The midfielder had achieved great success with Milan, but the club thought nothing of it when they let him leave on a free transfer.
The midfield maestro spent four seasons with Juventus and won the league title each year with them, reaching the Champions League final once. Ironically, Milan's downfall began after Pirlo left, while Juventus kept getting better and better and established themselves as the most dominant club in Italy.
#1 Robert Lewandowski - Bayern Munich
This one is a no-brainer. Although all the players on this list have achieved great success with their new clubs, no signing impacted the tangent of a league as much as Robert Lewandowski's move to Bayern Munich from Borussia Dortmund.
Under Jurgen Klopp, Lewandowski and Dortmund won the Bundesliga back-to-back and ended the Bayern hegemony in Germany's top division. However, in 2014, the Polish international decided to move to his club's direct rivals and joined Bayern. Since then, the Bundesliga has been a one-horse race.
Lewandowski has scored an astonishing 218 times in 262 appearances for the Bavarian giants, and they have won the Bundesliga every year since his move. Not only did Bayern strengthen themselves by signing one of the world's best strikers, but the Dortmund team were considerably weakened and have not managed to win the league since his departure.
Not only is Lewandowski the best free transfer of all time, he just might be the best transfer ever.