Despite those defeats, there were signs Marcelo Bielsa's men were getting back toward the level of performance that saw them reach the Europa League final last year and Muniain is confident if they keep improving the results will soon arrive.
He told Marca: "We need to know how to play these final minutes, to have a little more experience and conserve what it ours.
"We are playing well and feeling comfortable on the ball, but the results still aren't there. We have to take the positives and if we continue like this then the results will arrive."
Ander Herrera is suspended for the Basques after being sent off against Valencia last weekend, but otherwise Bielsa is expected to stick with the team that started in Lyon.
Getafe boss Luis Garcia also thinks Athletic will eventually climb the table, but is hoping to at least maintain the two-point advantage his side have over their opponents this weekend.
He said: "Athletic are a team that attack with many options and they have very good players. They will lose Ander who gives them different things, but they are one of the teams that ought to be in the top part of the table.
"We think they are one of the seven big clubs, but at the moment they are below us and we hope at the end of the game that remains the same."
Garcia will be able to welcome back top-scorer Abdel Barrada from suspension, while David Abraham is fit enough to take his place in defence, but Paco Alcacer is expected to miss out with a bout of gastroenteritis.