Joel Matip was part of Liverpool when this team gets champion League and Premier League title and he was joined with Liverpool for almost 8 years and for Thiago Alcantara he was joining since 2020 and Thiago also has help Liverpool to gets several trophies under Klopp so these players has a lot of contribution for Liverpool but indeed this season both players didn't playing regularly because they got injured especially Joel Matip that since the beginning of season he was got long term injured and maybe these factors too why Liverpool has decide will not extended their contract
I think Liverpool is trying to refresh the squad by getting rid of players who are injury prone like Thiago and Matip. They have done this last summer by letting go five players. Liverpool still have some injury prones in the squad like Alisson, Konate and Diogo Jota. Injuries have become a big factor that hold Liverpool back.
Refreshing a squad is a necessary thing to do top high competitive spirit within the team. Last season, Liverpool made a mistake by keeping many the same old players stay around when they actually needed fresh midfielders. There should be a policy with the fact of having injury prones in the team, they should not sign any player who has a bad injury record.
Of course, injuries are very detrimental obstacle for the team and when player with good quality is injured it causes each team performance to decline quite significantly, but the steps taken by Liverpool must be balanced by bringing in other players as replacements.
This season they performed very well until the end of the season arrived but after remaining few games Liverpool experienced series of problems which required them to suffer decline in performance and lose the opportunity to compete for the title.
I don't know what Liverpool will do in preparation for next season, but what is certain is that I believe they will get rid of players who really don't contribute much and bring in players who are much better, especially considering that there are several core players whose contracts are about to expire.
But personally, I would rate Liverpool as having fairly weak defensive performance, front line was more than enough to be able to break through every opponent defense, but Liverpool defense made several mistakes which gave them gaps to concede.
They do things like this quite often and the defense line is very important part of the strength of football team.