The ED of the second cour of All Out!! prominently features a lone girl (probably the team manager), seen from her back. She is looking onto a darkening field for well over 30 seconds. She is not moving, but the camera is. You can see this beginning at 23:05 of the provided link. The music seems sort of wistful, with a lone female singer. Through the latest episode (18), there has been nothing to provide this long take with a context.
Do the lyrics help explain this? Since they are Japanese with no sub, I have no idea what the song is about. I do like the singer's voice and the mellowness of the music. If the lyrics are not relevant, maybe something later in the series will explain. To this point however, the manager has only had a peripheral role. If manga readers know, please describe in a spoiler tag. At least I'll know to watch for it!