Maybe Atletico Madrid have made a really good progress to secure their position in top four but I don't think they are very safe now. The balances can change anytime depending on how good Real Sociedad and Betis will be in the rest of the season. But after watching Real Sociedad for many weeks I have lost my belief in them significantly to catch up with Atletico Madrid. It started to seem like Atletico Madrid will secure the third position for themselves and the last position for the Champions League will be between Real Sociedad and Betis.
About the last position I'm favouring Betis. I think they have more potential than Real Sociedad if they keep up a decent form. It is easy to close a gap of three points for them in that case.
Atletico are in good shape, but it is true that they are not completely safe because they have not too much gap. They should not pin their hopes on the competing team to get sub-optimal results. But they have to stand on their own feet so they can continue to be in their current position until the end of the season. They have that ability and they should be able to do well. Atletico Madrid is a team that has always been in the Champions League zone.