Cech was pushed out by new co-owner Todd Boehly after the club's sale.
Boehly has been acting as a de facto sporting director over the past few months – and while he has closed deals for Raheem Sterling, Kalidou Koulibaly, Carney Chukwuemeka and Marc Cucurella – Tuchel has suggested that the void of expertise is being felt.
“I still think we are in transition with a new ownership," he told Soccer AM when asked to sum up Chelsea's eventful pre-season. “Petr Cech out who was also such a big key factor, also for me in the season in the building here in Cobham, speaking with everybody and the staff and being a huge support for me.
“He's not here any more so there are some changes. We are positive but we are a bit in transition so we are excited but it comes pretty early (the season)."
Tuchel also reflected: "Normally I switch off, I train myself to switch off but this season it was impossible.
“New ownership, new communication, transfer period. We lost key players. It was not a summer like the last years and it felt a lot shorter than it actually was."