Currently, most of the Spanish clubs are suffering from finances which are hurting them badly, and they are not able to bring quality players just because of this having player like César Azpilicueta as free agent is good for the Atlético Madrid because now they are looking for the improvement as things are looking tough in next season while they will be competed with tough teams in Champions League and things are also not easy in La Liga even right now situation is also not good for the Real Madrid and Barcelona as suffering badly.
33 years old is good defender having long experience and quality will help them for improving their strength but still if they want to win title they have to give some intention for having improvement in their squad otherwise it's never been easy to stay at top level.
What happened that took La Liga teams in the last 10 years from being financially incredibly rich and talented and winning everything, to a place where only team with some money is Real Madrid, and everyone else is having trouble financially.
I understand the cap space thing and not allowing teams to buy players without first fixing the finances, that should be helping the teams but why did nobody cared? Like how did Barcelona became so bad like this? They should have been aware of their actions before they did it and where it will lead, how did that let it get this bad? Same with ATM as well, the yare getting worse and worse. At this point we may see them selling everyone and just fielding bunch of youth setup players for a season to get over this trouble.