The Germany international has been on the Stamford Bridge club’s books since the summer of 2012 but his switch to the West London club has coincided with the decline of a once-promising career.
After coming through the ranks at Borussia Mönchengladbach, Marin was highly regarded by the powers that be in German football and was earmarked as a player with the calibre to represent the national team.
Likened to Lionel Messi even in some quarters, the attacking midfielder’s technique, close control and vision in his days at Borussia-Park were a marvel to behold.
A switch to Werder Bremen in 2009 was seen as the next step in his path to superstardom and initially Marin starred for the Weserstadion outfit alongside Mesut Özil in the side’s midfield.
Over a two-year period between 2008 and 2010 Marin racked up 16 caps for Germany, no mean feat, and featured for Joachim Löw’s side at the World Cup in South Africa.
However, the promise that Marin showed in his early career has simply not been met, with injuries taking their toll along the way also.
Following Özil’s departure to Real Madrid, the Bosnian-born playmaker’s form dipped noticeably and it came as something of a surprise when Chelsea came knocking two years later.
The Blues had signed a player with raw talent in abundance, potential in spades, a unique skillset – but one who had not been playing well consistently for his club and who had been frozen out at international level.
Given the talent in the Stamford Bridge squad, competition for starting berths in the side was always going to be fierce and like many others in recent times Marin found first-team football hard to come by.
As such the German has only started two Premier League games for Chelsea since 2012 and has featured in a measly 143 minutes of action in total for José Mourinho’s men.
Firstly a spell with Sevilla bred frustration at a lack of chances to play, with only ten La Liga starts last term for Los Rojiblancos.
Marin was farmed out to Fiorentina in the summer in a move that promised much. The Florence side are undergoing something of a renaissance under Vincenzo Montella, and the German looked like a shrewd addition and something of a wildcard.
However, the former Mönchengladbach man did not step onto the pitch for even one minute in Serie A since the start of the campaign; unbelievably Marin was an unused substitute in 12 league games for the Viola this term.
His only opportunity to play for the Stadio Artemio Franchi side was in the Europa League, where he started two games and was introduced as a sub on two more.
Notably, Marin was only given one full 90 minutes of action during his time in Italy, against Dinamo Minsk in December, but did score two goals in Europe in his four outings.
With the 25-year-old clearly surplus to requirements in Florence, Marin has embarked on a new adventure in search of regular first-team football and will spend the remainder of 2014-15 in Belgium with Anderlecht.
Having represented clubs in Europe’s top four footballing leagues, moving to the Belgian Pro League could well be perceived as a step in the wrong direction for Marin.
However, given the fact that the German has only started 12 league games in total for three different clubs since the summer 2012, the winger needs an opportunity to play regularly if the promise he showed in his early career is to surmount to anything.
The defending Belgian champions have won their last seven games in a row in all competitions and are locked in an enthralling title battle with rivals Club Brugge.
Marin will feature in an exciting and youthful Anderlecht squad, but first-team football is not a complete guarantee given the likes of Youri Tielemans, Dennis Praet, Steven Defour and Andy Najar in the side’s midfield.
The German winger has certainly not lived up to his considerable potential and the chance of breaking into first-team contention at Chelsea looks non-existent.
However, a new challenge in Belgium offers Marin the chance to potentially play regularly and gives him the opportunity to prove himself and salvage a career that feels like a monumental waste of talent.