La Liga looks less competitive this season. And as you said, only Sevilla seems capable of competing with Real Madrid. Whereas usually Atletico Madrid and Barcelona are also in the title race and they often dominate the top 3 of La Liga but this season they seem to have lost their best performance.
It looks to be more competitive because they Atletico Madrid surprisingly did not play too well. Barcelona collapsed in surprise of all. It give chances to other clubs to take over the third position of Barcelona and make La Liga looks to be more exciting. Exciting in a chaotic season but in long run it is not good for La Liga. They must have Barcelona, Real Madrid and Atletico Madrid at their best in order to fight with other clubs from other nations, leagues in Champions League.
Barcelona have not been in the title race truck since the start of the season. Atletico Madrid played well in the beginning but now their performance is very irregular. They are also losing points against a relatively weak team. Only Real Madrid's performances are regular. Sevilla are playing well now but they don't seem to be able to win the title. In a few days they will lose form and fall behind than Real Madrid. They are now 5 points behind of Madrid.
Barcelona did not in this race since start or even before it because they lost Messi. Even with Messi, they still don't have good chance to win in the race. With Messi, they can join in title race but they will be in third position after Real Madrid and Atletico Madrid.
Now, their issues are worse even Koeman and Messi left. Xavi took over the coach position with many weaknesses and he also has his weakness as a newbie in coach career. I don't think Xavi can help Barcelona to reach to anything big in this season. A position at the end in top 4 would be a big achievement for Barcelona and Xavi. I don't think they can do anything bigger with what resources they have now.