Atletico Madrid played well but they have to fight against two strong competitors Real Madrid and Barcelona, and this title competition is very tight among three strong candidates. Their performances in La Liga can affected more or less, or even seriously by matches in Champions League. It's interesting that Real Madrid and Atletico Madrid have to face directly in Champions League and only one of them will be in quarter final phase.
The club that has to leave Champions League after round of 16 will be able to focus more on La Liga, and La Liga title competition will have big changes after round of 16 ending. It's likely that Atletico Madrid will have to end in Champions League while Real Madrid and Barcelona will move next, then Atletico Madrid will have better concentration on La Liga than two competitors.
I also have the same thought. When both teams have to meet in the Champions League, then one of them will definitely be eliminated early, so whoever it is will have an advantage in La Liga as they will no longer focus on many things, and they will have more time to rest (less games to play).
If it's Atletico Madrid, then they should really be able to take advantage of that situation, as they also have some good chances to overtake Barcelona, where they will still face Barcelona face to face (Atletico Madrid must win the match), and there is still El Clasico game, which can give Atletico Madrid an advantage (if it ends in a draw).