For defense problems, it seems that Xavi is giving too many experiments that make this not very good for them, such as when sometimes putting Kounde or even Cancelo in different positions which makes their performance not 100 percent maximum because they have to adapt to a new position besides that, this is like what @red4slash said indirectly Barcelona's performance and the attack patterns they make are what makes the defense disturbed.
We know that with the tiki taka that occurs, the quality of Barcelona's attacks, especially when especially when trying to control the rhythm, there will definitely be a lot of players who must be ready in attack, making some of their defenders inevitably have to help attack which makes their defense a lot of gaps that can be exploited.
This is what happens when their attacking patterns are read and indeed conceding 19 goals at the moment is a problem especially when compared to before where they were so strong that they even conceded only 20 goals in 38 games played last season.
In this match Xavi also did the same thing by playing Cancelo in a position that was not his best position We know that with the tiki taka that occurs, the quality of Barcelona's attacks, especially when especially when trying to control the rhythm, there will definitely be a lot of players who must be ready in attack, making some of their defenders inevitably have to help attack which makes their defense a lot of gaps that can be exploited.
This is what happens when their attacking patterns are read and indeed conceding 19 goals at the moment is a problem especially when compared to before where they were so strong that they even conceded only 20 goals in 38 games played last season.
Actually if I look at the current composition of the players, i prefer to enter Kounde as a right fullback and restore Cancelo's position at left fullback to replace Balde.
Balde is a pretty good player but he is a slow player so this could be a problem when the fullback is too far in the opposition defence he won't be able to get back to his position properly when the counter attack is launched.
At the moment the first half between Barcelona and Almeria is over and the score at the end of the first half is 1-1. Of course this must be a concern because if in this match Barcelona still fail to win full points then their position in terms of points could be even further away from Madrid and Girona.
Talking about Balde and Cancelo I would agree with what you said if we talk about the speed issue because seeing from what is happening right now Balde still cannot be compared to Cancelo but on the other hand another possibility of Xavi trusting Balde more is to give him flight hours because we know that even though Cancelo is very good in the game and speed but he will only last 1 season which of course if there is no habit and time for Balde from now on maybe it will be complicated for Barcelona in the future.
In yesterday's match Barcelona seemed to be still very troubled to maintain their performance, especially for defense problems. They struggled to face Almeria and almost even played a draw in this match if Sergio Roberto did not become a hero with his Brace in this match.