He featured just 15 times in all competitions, as poor form and injury problems cost him a place in the first-team.
This summer, with Kevin de Bruyne and Andre Schurrle now at the disposal of new boss Jose Mourinho, his time looked up.
However, at 24-years-old, Chelsea would be remiss to give up on him just yet - so instead they sent him out on loan to Spanish outfit Sevilla.
He impressed in pre-season at the Sanchez Pizjuan, and last night highlighted his ability in a superb performance against Slask Wroclaw in the UEFA Europa League play-off round.
Sevilla won 4-1 on the night against their Polish opposition - and Marin found the net twice in an excellent individual display.
He scored in the 67th and 89th minutes to help secure the comfortable looking first-leg victory - with Ivan Rakitic and Kevin Gameiro adding the other goals on the night.
Sevilla, who only qualified for European competition this year because of Malaga and Rayo Vallecano’s suspension for financial irregularities, now have one foot in the Group Stage proper of their continental campaign this season.
And while there is currently not enough room for him at Stamford Bridge, he could prove a hero in Seville.
Here are the goals from the game …
image: © 2e14