Speaking to Turkish outlet Hurriyet, Fenerbahce president Koc said: "Why did we let go of Mourinho? I'm explaining it here for the first time. It was a bitter parting. Our chemistry was perfect, and his accomplishments are evident. Just being able to bring him here was a great achievement.
"Above all, it was difficult to part with someone I was friends with. We knew our coach was a defensive player when we brought him in. But we talked about the need to play more dominantly at the end of the season. Earning 99 goals and 99 points is our genetic code.
"Being eliminated by Benfica wasn't a problem, but the way we were eliminated was unacceptable. This made me feel like last year's football would continue.
"We parted ways because we believed this squad would play better football at this point. This kind of football works in Europe, but in Turkey, we have to crush them in most matches. We're struggling to get ahead after falling behind in every match."