Arsenal were in a really bad situation when Arteta took over. They were not playing legendary football like in previous years. Despite this, it managed to become very successful in a short time and now appears as one of the biggest teams in Europe again.
There is a similar situation in Chelsea, actually the situation of the team is not so bad but they cannot achieve success. Towards the end of the season, their performance increased significantly and they started not making mistakes. Maybe they'll manage to continue like this next year
Chelsea did well towards the end of the season but it was a bad end for them after they were not given the opportunity to play in the Europa league despite finishing in a position that is deem fit to make them qualify. Chelsea sacked their coach after the season, this was what no one saw coming and have signed a new contract with Maresca, Leicester City’s former coach that brought them back to the premier league after the relegation. I am expecting Chelsea to do better this coming season and this is not something they should joke with to avoid disappointments like they did in the last season. Chelsea needs to improve their performance but they keep failing but after last season I’ve seen much improvement in them and will do well next season in my opinion.
Although Chelsea did not start the season well, this team played very well at the end of the season. The interesting fact is that Chelsea won the last 5 matches of the season. Still I don't know why Chelsea management sacked Pochettino. Chelsea's overall performance is poor due to some bad decisions by Chelsea management.
If you change the coach every season, nothing good can be expected from the team. Coaches also need time to get to know the players. At the same time, players need time to adapt to the new coach's match strategy. But the Chelsea management is not interested in giving this time to any coach. This is why we have seen such poor performances from Chelsea over the last few years.