However, a conversation with manager Enzo Maresca convinced him to stay this season.
Ahead of their Europa Conference League clash with KAA Gent, Casadei said: "To be honest at the start of this season I was thinking about what was the best solution for me.
"I think last season was quite difficult, especially the last six months, because I didn’t play a lot. I was not really happy, because everyone wants game time.
"But from the moment I spoke to the manager I was 100% sure that the decision to stay was best for me to improve and for my career.
“I didn’t want to go permanently. There were some possible loans. But I have always wanted to play for Chelsea. We are one of the biggest teams in the world so I could not be more proud to play for Chelsea."
On the midfield competition, Casadei added: "We are at Chelsea, so it’s normal there is a high level of competition.
"There's so many good players, as it should be. So not always easy to play week in, week out. You have to get it in your mind that you will have to fight for your place.
"That is why I decided to stay. When there is good competition it can make you a better player and help you to improve.
"My goal is to become a Chelsea player — an important player for this team. I always try to give my best to the team, to try to train hard every day and keep improving, having the goal to become an important part of this team."