Atletico really underestimate Elche.
Moreover Atletico also didn't play as best as they are usually. Tjey cound't domimate the match and not really ready with the match. Seems like to be this. That is why theybwere lost.
Btw, because if Atletico loss and Real Madrid victory, now Real Madrid becomes on their second position as runner up in La Liga.
Atletico played not in their best form, they won the ball possessions but they don't get many chances to score. During the match, they only got 4 shots on target. Even, Elche could make more shoot attempts and they succeed to score 1 goal. With this result, Atletic must drop their position in 3rd place. Now, Real Madrid returned to 2nd place and probably stay there until the season ends. Atletico Madrid really wasted the chance to finish in 2nd place.
Elche and Atletico have almost the same opportunities. Atletico didn't get many chances with good finishing and the stalemate up front was their fault.
This was surprising when the line-up was applied to Atletico. They couldn't even score 1 goal to even the score. although not in danger of being eliminated from the top 4 standings. but losing to a team that is bottom of the relegation zone is not good for Atletico.