Werder Bremen sporting director Klaus Allofs expressed his belief that the German international's skills did not suit the style of the club after he signed a deal with the Blues.
The German international will move to Stamford Bridge when the transfer window opens again in June and has penned a five-year deal.
"There is nothing greater than Chelsea. I'm very happy the transfer worked," he told Bild.
Meanwhile, Bremen sporting director Klaus Allofs stated that Marin had not developed into the player the club had expected him to after joining from Borussia Monchengladbach.
He also expressed his belief that the attacker's style did not suit the German outfit and indicated that he had rejected a new contract at the Weserstadion.
"Marko's development was not what we had imagined," Allofs said. "He has his strengths, but they are not the ones we need at the moment. An extension was not an issue as he indicated to us."
The sporting director went on to rule out Chelsea striker Romelu Lukaku coming in the other direction, but suggested another Blues player could be on the move
"Chelsea have other plans, but I will not rule out another player coming to us," he added.
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