The Liga side had already exited the competition prior to Tuesday's 1-0 defeat against Bayer Leverkusen at La Anoeta.
However, Omer Toprak's goal in the second half ensured Sociedad ended the group stage without a win, and with just one goal from their six matches.
Despite that, Arrasate claimed their European journey has been of benefit to the squad.
"The campaign has served us well in terms of our growth and evolution as a team," he said.
"We've played in the best club competition, the most demanding. We did some positive things."
Sociedad also missed out on Europa League football in the new year, having finished seven points behind third-placed Shakhtar Donetsk.
Arrasate feels his side deserved more from their campaign but was wary of using excuses to mask a disappointing group stage.
"We wanted to play well and to win, but the victory was not to be," he added. "We were at a good level, though. You always hope things will turn out better.
"There have been games where we deserved more, but we have a point to show for our efforts in the group and I don't want any excuses."