If you have a 7th you can use it to give a young starlet an experience of first team away games, if you have 7 it means that you can effectively cover every single position and then some. It simply decreases the chances of having to play people out of position. Why in any world would you not have 7 players on the bench? Its Cotts making a point that has already been made. Lloyd Kelly would've been a nice person to have on the bench, he can cover Baker and Bryan.