The winger has spent this season on loan with Unai Emery's squad after failing to break his way into Jose Mourinho's first-team plans at Stamford Bridge and, despite failing to live up to his long-term plan with the Blues, his inclusion at Ramon Sanchez Pizjuan has helped to lift the side into seventh spot in La Liga.
The side sit just ten points behind fourth-placed Athletic Bilbao in the Champions League play-off spot and, hoping to maintain European football at the club, Emery's men sit just six points behind sixth-placed Real Sociedad in the final Europa League qualifying place.
However, consolidating the side's current position will be enough to retain European football for Sevilla next season as both Real Madrid and Barcelona's place in the Copa del Rey final means that seventh place is open for an extra Europa League spot.
Per WhoScored's tweet, Marin has been influential with his passing in Europa League action this season, and will be hoping for more of the same against Real Betis in the Round of 16:
German midfielder Marin, who joined Chelsea from Werder Bremen in 2012, has failed to establish himself in the English game and looks hopeful of returning to Spain on a permanent basis, should he remain fit and in the first team, speaking with Estadio Deportivo (h/t Daily Mail's Nick Lustig):
If both Sevilla and me are happy to stay I can stay here forever. We'll see what happens in the summer. The first is to play, being fit and helping the team in the end of the season and then we will decide.
If the fans want, Monchi (the sporting director) wants and the coach wants, why not? But the most important thing is to be fit and play. Speaking about a permanent move before that is not worthy because I can't help the team if I do not play.
Marin's first-team opportunities look all-but-over at Chelsea, with the squad brimming with nine midfielders—with Andre Schurrle also operating from an attacking-midfield position for Mourinho's men, as Ramires, Frank Lampard, Oscar, John Obi Mikel, Mohammed Salah, Marco van Ginkel, Eden Hazard, Nemanja Matic and Willian remain in the current squad.
Add that to the Blues' on-loan contingent of Oriol Romeu, who is currently with Valencia and Josh McEachran, situated within Wigan's first-team plans in the Sky Bet Championship, the 25-year-old would be better off looking for a permanent move away from the London club.
The playmaker could yet win the Europa League with his current side this season and cap off an excellent first year in Spain, adding to his four assists in 16 combined league and European appearances, with an excellent 82.2 percent pass succession rate across both competitions, per WhoScored.
A move away from the Bridge could also boost the midfielder's long-term chances within the German national team, as he competes with the likes of Bastian Schweinsteiger, Mesut Ozil, Toni Kroos, Schurrle and Mario Gotze for a place in Joachim Loew's squad.
Selling Marin could also have financial benefits for Chelsea, too, as UEFA look to crack down on elite clubs through Financial Fair Play, which sees each club needing to monitor their wage bill, and exits for players like Marin could ease the Blues' wage bill to meet with regulations.