People have the misconception that when we talk about experienced players we're referring to old and 30+ players. Many experienced players are 25-28 years old. Players that can give you 4-6 years of top-level football. Those are the kind of players Chelsea are supposed to be going after, instead, they sign only players that are 22 and below. I'm not saying it's a bad thing, but when the whole team is filled with kids, they can't succeed.
If we look at the players Chelsea have signed since this new management took up, they're more than 20. How do you sign over 20 players yet none of them is a proven world-class player? What do they win to achieve? They can't be title contenders with a squad like that, they may manage to get to the top 6 and with a very good manager they might get the top 4 but they won't contend for the title.
Chelsea has long become like an experiment, they change things too often, which is why the experienced players you are talking about either left the team or don’t really want to participate in it. We don’t know how good Maresca will be in Chelsea, but he won the Championship with Leicester, which is more of an achievement, but the Premier League is a tournament of a different level and what may have worked with Leicester will not work with Chelsea, which is very much inferior in squard to the top teams.