Add a data view for the team entity as top level object.
Add a layout grid with 2 columns divided 50:50 to the dataview.
Add a second row to the container and place text widgets in the first row.
In the second row place the fields for the team on the right and a listview or datagrid on the left.
Make sure the data grid shows the players over the association with the team.
Implement a microflow to validate the team object when saving and retrieve the players from the team and commit the objects for the player and the team.
When you need this kind of setup more often you might consider creating a layout for this purpose (see: https://docs.mendix.com/refguide/layout/)