You can get caught up in these thoughts – that it was maybe a big mistake to let him go. But you never know," he said.
“You don't know what would have happened if he had not changed clubs. Maybe it was the right thing for him. It's hard to tell."
“You draw a comparison to Kai and Timo's situation. It's always a process. For some it's faster, for some a bit slower. We will never lose patience," he said.
“As long as they are Chelsea players they get full support. The league here, you step up and adapt or you don't. If you don't, you don't make it in this league.
“That's why I'm very happy that Timo and Kai stepped out of their comfort zone and took this adventure. They took this huge challenge.
“This is bravery, to bring out the very best. It sharpens their character and mentality. They are on their way. We will push them."