The players_id is not important when it comes to the database. (It might be important for getting player names though - depending on your code) What is important is the players names, because that is what the public will see on the fixtures public page. You need to have positions and fixture id's in your selections table
Selection_id, Fixture_id, Batsman1, Batsman2, Batsman3 etc.
1 1 John White, John Blue, John Brown
You need to figure out a way to get those player names assigned to those positions in the table.
As things are, you are trying to enter one value into three columns, through loops,without making any associations at all.