It has been a disastrous season for Real Madrid, and Marcelo has perhaps been the perfect encapsulation of their struggles as he has performed significantly beneath his usual standards.
The Brazilian has unarguably been the world's standout left-back over the last five years, earning praise from all and sundry with his explosive runs down Los Blancos' left channel as countless goals were scored off his pinpoint deliveries.
This season has seen the 30-year-old struggle to match his previous heights as he has been constantly at fault for lots of goals conceded by the club this season, while he has also underperformed in his attacking output.
His subpar displays led to him reportedly led to him apologizing to his teammates in the dressing room, while he also issued a public apology to the fans after the shock 2-1 defeat to Girona at home in La Liga.
Indeed, it was suggested that Girona coach Eusebio Sacristan specifically targeted the Brazilian international's flank and even though the 54-year-old publicly denied this, his tactics suggested otherwise, as he switched Portu to the right flank at the start of the second half, with both their goals coming off attacks from that wing.
Marcelo finds himself facing scrutiny over his performances for the first time in his Real Madrid career and it is a scenario he is not used to. In this piece, we shall be taking a look at five factors which have contributed to Marcelo's struggles this season.
#5 Ronaldo's departure
It has long been established that Cristiano Ronaldo does not have close personal relationships with many of his teammates as he prefers to operate on a professional level with most of them. However, one exception to that rule is Marcelo.
The pair were mainstays on the left flank of Real Madrid for almost a decade and developed an almost telepathic connection on the field, with Ronaldo almost always knowing how to time his runs to perfection and meet Marcelo's crosses.
It was a scene we saw time and again - Marcelo lining up a cross from the left flank and Ronaldo, at the back post, nodding it home before performing his trademark "si" celebration.
Most times, Marcelo was the first person Ronaldo sought out when celebrating, while the two of them also performed the double version of the si celebration at times.
However, their relationship goes beyond just having a connection on the field as Marcelo is also one of the few players with whom Ronaldo has a personal relationship with.
Since he has arrived Juventus, Ronaldo has come out in public to squash rumours linking Juventus with other players but he went ahead to issue an open invite to Marcelo by stating that the Brazilian would be welcomed in Turin.
Ronaldo's departure from Real Madrid robbed Marcelo off not only his partner-in-crime on the field but also one of his closest friends, and this could have created an emotional void that he is struggling to fill.
#4 Injuries have been unkind to him
Football is a contact sport and as with all other contact sports, the chances of players sustaining injuries are rather high.
Muscle tears, torn hamstrings, bone dislocations are among the more common forms of injuries suffered by the football players.
Injuries come in different ways - from a mistimed tackle to the shock of an unexpected sprint. Footballers can be injured during harmless training sessions as well. Some players are luckier than others in having relatively injury-free careers, while some are beguiled by injury problems which ruin their careers.
So far this campaign, Marcelo has had rotten luck with injuries, having sustained three different injury setbacks which saw him ruled out for 55 days in total, missing 10 matches in the process.
Injuries take a massive toll on players' bodies and they are sometimes never the same upon their return. And with the Marcelo sustaining several injuries this season, it is only natural that his performance level has taken a hit.
#3 His teammates have also struggled
Real Madrid were knocked out of the Copa Del Rey, saw their hopes for La Liga glory dashed and were eliminated from the Champions League in the space of six days, with all of it happening at the Santiago Bernabeu.
While Marcelo might be one of the most underperforming players in Real Madrid, he is definitely not alone as his teammates such as Sergio Ramos, Karim Benzema, Isco, Marco Asensio, Luka Modric, Toni Kroos and Gareth Bale have also failed to reach their previous heights in the present campaign.
Although football is a team sport, a good individual performance often rubs off to other players. Hence, when several Real Madrid players are in top form, they invariably make the rest of their teammates look good. However, Real Madrid players have struggled for form this season and the poor performances of his teammates has also affected Marcelo.
#2 The form of Sergio Reguilon
Sergio Reguilon first made headlines in October last year when he was the subject of a viral video which showed Sergio Ramos reacting angrily by kicking a ball at him twice during training.
Ramos's actions were largely condemned, but subsequent posts by the pair suggested that the matter had been buried.
While many people might not have known who Reguilon was back then, the 22-year-old is well-known by now as he has gone on to cement his place as Real Madrid's first choice left-back.
Reguilon joined Real's youth setup in 2005, aged just eight, and progressed through the ranks until becoming a main starter in the Castilla side under Santiago Solari.
He was promoted to the first team at the start of this season but found playing time under former boss Julen Lopetegui hard to come by. He had to wait until October to make his senior debut, just a few days prior to Lopetegui getting the sack.
However, his stock has improved since the appointment of his former youth team manager as the first-team boss as he has seen himself being installed named the first-choice left-back, following Solari's dropping of Marcelo. And Reguilon's performances have suggested that the Argentine gaffer made the right choice.
This is in no way to suggest that Reguilon is a better player than Marcelo (he has a very long way to go before even thinking of that), but at the moment he is doing plenty to suggest he deserves a starting spot ahead of his more experienced teammate.
While Marcelo might boast better stats in the attacking areas this season, Reguilon has made more defensive contributions, including winning more tackles and making more interceptions per 90 minutes.
Marcelo contributed in no small measure to the history of Real Madrid but it is increasingly looking likely that Reguilon is the club's future. For as long as the 22-year-old keeps up his impressive performances, Marcelo might find himself out of the first-team picture.
#1 It's only natural
Marcelo has been a top-level professional at the highest stage since 2007 when he joined Real Madrid, and he arguably came into his own as a world-class left-back around the 2011/2012 season.
During that time, the Brazilian international has gone on to win almost every available trophy in professional football, hence there must be a drop in the motivation level for him as there is almost nothing left for him to do.
Marcelo has spent the last six to seven years as the best player in the world in his position, and having been at the top for so long, there is nowhere else to go but down (the law of diminishing returns).
A player normally spends an average of between five to seven years (usually between ages 23 to 30) at the very top of their games. They go from progressing as a youngster with a lot of potential to becoming established superstars before their performances start to decline.
This is a trend we have witnessed countless times throughout the history of football and it is one that is likely to continue.
As the saying goes, you can't cheat nature and with Marcelo having been at the top of the game for so long, it is only natural that he begins to witness a decline in his performance level.