UCL is just another excuse by Arteta. When you compare his club to the Liverpool, it's totally different. His club is still far away from winning UCL, meanwhile Liverpool is a few steps closer to PL title. He's also walked out after the journalist asked him about PL title challenge against Liverpool.
That's why he said that to avoid being blamed or mocked by his rival. The better you wait until his club leave from UCL, then see what's gonna happen with him.
Everyone seems to be interested in Arsenal affairs and how well Arteta is doing with the club. Losing the Premier League title for the third consecutive season is sad but he is pushing on with the team and that is all that matters. The Premier League title race has been lost already, all focus is shifted to the Champions League and achieving the unthinkable lol.