10 stars who saw the biggest drop in market value in the past year

The key to having a great career in football is consistently hitting highs and delivering whenever required. It's no easy task, though; loss in form, injuries, or their inability to adapt to new systems see even the greatest players fade away into relative obscurity.

Sometimes it is bad luck, sometimes it is just age catching up. At the same time, it also sees these players become potential transfer targets for cut-price deals.

So which players saw the biggest drop in market value in the past 12 months?

Note: Data taken from TransferMarkt.

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#10 Carlos Bacca (AC Milan / Villarreal CF)

Market Value at the start of 2017: €25m

Current Market Value: €12m

There was a time when Carlos Bacca was tearing defences apart in the Italian Serie A in his two-year stint at AC Milan. After impressing with Sevilla, Milan saw it fit to activate his €30m buyout clause and it seemed like good business at the time.

Bacca was the undisputed star in a rather underwhelming squad that was going through a rebuilding phase. Villarreal decided to take him on loan this season but the Colombian has failed to hit the heights he did with Sevilla and Milan.

The 31-year-old has scored just 5 goals in 18 appearances this season. He used to be the primary goal threat at his previous clubs but he now plays second fiddle to Cédric Bakambu who is the club's top goalscorer (9 goals) despite playing fewer games.

#9 Jesus Navas (Manchester City / Sevilla)

Jesus Navas

Market Value at the start of 2017: €20m

Current Market Value: €6m

Another player who made a name for himself at Sevilla, Jesus Navas is one of those Spaniards who failed to truly realise his own potential.

A speedy winger who could set fire to the flanks soon became predictable and was seen as a one-trick pony - one who always took the ball to the goal line before sending in a cross.

Navas was never a goalscorer but he was a provider. He'd proved that at Manchester City with a number of assists at his peak between 2013 and 2015. He was used quite often even in his final season until he returned to Sevilla when he barely played last season and Pep Guardiola had no use for him this season.

Now 32, his drop in form is alarming. In 16 appearances, he has just one goal and zero assists.

The Andalusian side have not exactly impressed this season, sitting in sixth place after the sacking of Eduardo Berizzo. Vincenzo Montella has come in but it remains to be seen if he can get the best out of him.

#8 Angel Di Maria (Paris Saint-Germain)

Angel Di Maria

Market Value at the start of 2017: €55m

Current Market Value: €40m

When Angel Di Maria left behind the nightmare that was his season at Manchester United, things were looking up for the Argentine winger. After scoring just 4 goals at Old Trafford, he was back on the score sheet regularly with 29 goals in his first two seasons.

His stock rose again and he was coveted by a couple of clubs even though he was quite happy to play in Paris. Then came the bombshell from PSG when they signed both Neymar and Kylian Mbappe - players who play in Di Maria's position.

Suddenly, the 29-year-old became a bit-part player and he has only made 11 starts in the league this season with 3 goals and 4 assists.

However, he has made a great start to 2018, scoring 3 goals in as many appearances. But this may be just a temporary phase until the trio of Neymar-Cavani-Mbappe start together more regularly.

#7 Gareth Bale (Real Madrid)

Gareth Bale

Market Value at the start of 2017: €90m

Current Market Value: €75m

The rise of Gareth Bale and Neymar pretty much ran parallel to each other. Both players were signed by Real Madrid and Barcelona respectively in 2013 and the comparisons were always going to be made.

Although Bale trumped Neymar in terms of major trophies won (three Champions League titles saw to that), the Brazilian is now the undisputed star with the potential to usurp Cristiano Ronaldo and Lionel Messi of the Ballon d'Or crown.

Bale, on the other hand, has suffered a number of injuries over the years and 2017 was no exception. The Welshman has missed more than 80 games since his transfer to the Bernabeu.

The 28-year-old has only made 9 starts in all competitions for Zinedine Zidane's side but he is slowly finding form having scored more goals than the struggling Karim Benzema. Whether he can improve further and possibly move back to the Premier League in a big money deal remains to be seen.

#6 Santi Cazorla (Arsenal)

Santi Cazorla

Market Value at the start of 2017: €20m

Current Market Value: €5m

Santi Cazorla's story is probably the most heart-breaking of the lot. One of the finest midfielders of his generation, the diminutive playmaker was the one player everyone in the Arsenal squad looked up to.

Nobody personified Arsene Wenger's famous style of beautiful football better than Cazorla. It is no surprise that the beautiful aspect in Arsenal's game has suffered after he was sidelined with injury.

The 33-year-old has undergone numerous surgeries in his foot - first to fix his foot, then to take care of an infection that developed which almost led to amputation. His forearm skin has been used as a graft on his foot and he is still no closer to training, let alone playing.

Arsenal gave him a one-year contract extension as a sign of goodwill but with no end in sight to Cazorla's troubles, he may be let go at the end of the season - which would be a sad way to go for a player who gave so much to the north London club in their pursuit of ending a long trophy drought.

#5 Wayne Rooney (Manchester United / Everton)

Wayne Rooney

Market Value at the start of 2017: €30m

Current Market Value: €15m

13 years at Manchester United were enough for Wayne Rooney to become the club's top goalscorer. And it was in his final season with the Red Devils that he managed to get past Sir Bobby Charlton's previously elusive mark of 249 goals.

By the time Rooney left, he had 253 goals. But he had hardly played, making just 15 league starts and was largely used as a substitute by Jose Mourinho who preferred to ease him out of the squad rather than drop him altogether and face the supporters' ire.

To his credit, Rooney himself knew his time had come. A move back to Everton was the logical choice with no top club looking to sign an over-the-hill forward. However, he wasn't done just yet.

He has recaptured the goal scoring form that had deserted him after the 2013/14 season and he is the club's top scorer this season.

At 32, this could be Rooney's final club in the Premier League before he decides to hang up his boots or move abroad to a league that is far less challenging. The Chinese Super League were reportedly ready to spend big to bring him there but the move never materialised.

#4 Arda Turan (Barcelona / Istanbul Başakşehir)

Arda Turan

Market Value at the start of 2017: €28m

Current Market Value: €12m

In hindsight, Arda Turan's transfer to Barcelona was arguably one of the worst pieces of business done by the Catalan club. The Turkish midfielder never settled in and was never a sure-shot starter in the Barca lineup.

He was a fine player in his mid-20s with Atletico Madrid - a combative midfielder with an elite big-game mentality that helped the Rojiblancos win three major trophies - including a La Liga title that broke the Real-Barca duopoly.

But at Barca, the £24.1m transfer failed to hit the same heights. He was predominantly used in games against smaller opponents or cup games. Sitting out for six months twiddling his thumbs when Barcelona weren't able to register him due to a transfer ban at the time had also taken its toll.

This season, Ernesto Valverde hadn't even given him a single minute on the pitch as he continued to earn high wages. Desperate to get him off their books, he has now been sent on a long-term loan deal at Istanbul Başakşehir.

#3 James Rodriguez (Real Madrid / Bayern Munich)

James Rodriguez

Market Value at the start of 2017: €70m

Current Market Value: €50m

Barcelona aren't the only La Liga club to cut their losses. Arch rivals Real Madrid have tried to move James Rodriguez on for the past year (if reports are to be believed) and they were finally able to send him on loan to Bayern Munich.

Zinedine Zidane just couldn't figure out how to make use of the Colombian midfielder. When he burst on to the scene as a youngster in the 2014 World Cup - walking away with the Golden Boot - he was a prized asset and Real saw it fit to spend £71m.

He has had his moments but his career at the Bernabeu hasn't exactly gone to plan. With Isco and the young sensation Marco Asensio improving and impressing Zidane, James was an expensive backup who made only 13 La Liga starts last season.

A two-year loan deal at the Bavarian club seemed like a win-win situation for all parties and James also seems happy with his performances so far - scoring 3 goals and grabbing 4 assists in 10 starts.

At Bayern he has the chance to improve his market value and Real will be the ones who could eventually sell him for a decent price when he turns 28.

#2 Vincent Kompany (Manchester City)

Vincent Kompany

Market Value at the start of 2017: €30m

Current Market Value: €10m

Yet another player who has been victim to recurring injuries is Manchester City's captain Vincent Kompany. The Belgian defender was a key player in their two league title triumphs but has since seen the number of appearances he makes a season drop.

Time and again we have seen the now 31-year-old defender go to ground clutching his leg before shock gives away to disappointment.

For a player who averaged nearly 40 games a season, Kompany now averages less than 20. He has not been able to play a string of games to reclaim his form.

Since the start of the 2015/16 season, Kompany has suffered 10 injuries that have kept him out for anywhere between 1-4 months. He may be worth just €10m now but it is hard to see any top club looking to sign a player with recurring injuries to his calf muscle, groin, and knee.

#1 Thomas Muller (Bayern Munich)

Thomas Muller

Market Value at the start of 2017: €75m

Current Market Value: €45m

Make no mistake; top clubs in Europe would be delighted to bring Thomas Muller on board even though he has seen the biggest price drop in the transfer market. No other player has seen a €30m drop in value.

Muller has struggled in the past year - so much so that even Bayern Munich CEO Karl-Heinz Rummenigge came out and said he had to improve (even though he ruled out a possible sale).

For a player who regularly averaged 25 goals a season between 2012 and 2016, Muller scored just 9 in 42 appearances last season. This season has seen him score just 4 in all competitions (2 goals in the Bundesliga).

At 28, Muller should be playing at the peak of his career. Carlo Ancelotti's tenure saw him benched regularly but Jupp Heynckes' return has seen him slowly bring Muller back into the fold.

With a World Cup coming up, Muller needs as much game time as possible if he is to chase down Miroslav Klose's record of 16 goals. Muller is currently on 10 goals.