He said: "It's been a tough week with the departure of one manager and the arrival of a new one.
"I have a really good relationship and get on well with them both.
"The six months I spent working with Frank were fantastic. And I had two unbelievable years with Tuchel in Paris too, including getting to the final of the Champions League.
"It's been a really unique week for me, different to anything I've experienced before, because when managers have changed before, the incoming coach has never been someone I've already worked with, who I already have such a good relationship with.
"It's always been new managers who I've not worked with before. So I'm left with mixed feelings. Sadness for one, happiness for the other."