Chelsea fits in that 4th position more, Villa are currently in a good form also but Maresca seem a little further in terms of delivering major performance to hold that position. Chelsea are not coming for the title this season, they are not yet up to that level even Maresca said so, but next season, undoubtedly we might get to see Chelsea in the top 3 competing for the title.
These season is currently for City and Arsenal, Liverpool has the option of 2nd place or third place but not just for the title because i see Arsenal as a much stronger contender. City are not too healthy in the league, their performance has been below expectations and meaning anything can be possible to favor Arsenal except they come back to their best performance.
I will agree that three clubs are the favorite which are Manchester City, Liverpool and Arsenal but this season Premier League has gone to the next level, last season fourth club is Aston Villa and this season Chelsea are really fighting for that position even when you said Chelsea was not ready I doubted it, the season is not that far I still expect Chelsea to get to the top because they are just four points away from the top, I understand Maresca for saying that because when he started saying something like that many expectations will come and there will all be waiting to see the end but when he said they're not ready I like his courage but don't be surprised he also have target.
The real competition will starts after the international break because checking the table Liverpool are leading with 18 point, Manchester City and Arsenal have the same point, Chelsea and Aston Villa have the same point, Brighton and Newcastle have the same point, Tottenham, Nottingham Forest and Brentford have equal points also, West ham, Manchester United and Leicester City have the same points, I hope you can see why I see is going to be competitive.