Not only do they miss their team, but they miss their function within the team and the sense of purpose and accomplishment they gained from being a member of that unit.
People's families are like teams. Whether they are functional or not, one's family members constitute a team with which a person feels more or less close. Even though you may not like your team, it's still your team and you belong there, whether or not that's a comfort to you. When you lose members of your team, you grieve for more than just the loss of that person. You are also grieving for your team.
Recently I lost both surviving members of my family nearly at the same time, and that has proven hard, not only because I miss the people they were, but also because they were my team. I no longer have a team to belong to and so I feel that loss too. I no longer have a place and a purpose within that team and so I feel diminished. Like the NFL players who miss their team and seek to replace it, I need to replace my team with a group of people who will provide me with a purpose and a sense that I can contribute to that group in some important way.
I've never considered my family as a team because we all had bad brain chemistry and so most of the time we were at odds with each other, feeling fear and anger much of the time, coupled with a longing for more closeness, for real acceptance and a sense of unity that never seemed achievable for very long. But we were a team, and did feel that we belonged together, even if it was because we were all miserable. When you're part of such a team, you get some satisfaction from being screwed up together. But unfortunately, it gives you a skewed view of what it means to be part of a team.
I think that's part of the reason why children who are abused by their parents and other family members express outrage and despair when they are taken away from those terrible people, even though the child is likely to end up dead or permanently traumatized. People who don't grow up that way don't understand it, because they can't fathom how anyone would want to be a member of such a toxic team. But you don't choose your original team, and it's hard to conceive of being without it; you don't see the foster family or the family you are currently staying with as your team. It's another team, and you might even see it as a rival team.
That people can hold such views is puzzling to people who grew up in a nice, helpful, well-functioning family. They believe the virtuous qualities of their family make them a strong team. They don't consider that it's mostly because they were born into this team and don't know any different that they want to hold onto it and to try to persuade others to leave their less healthy family group. Of course they're right to like being in a good family, but it's just luck that they were born into a functional instead of a dysfunctional team.
Anyway, it's kind of a revelation to me to realize that I do belong to a team after all, and that I had a purpose and a role in that team and now my team is gone and I'm alone and missing having a purpose in life. So like those NFL players who are sad because they miss playing football, I'm going to strive to find a replacement for my team.