That is 40% true for me. The manager decides on the tactics to be used in the gameplay. The efficiency of the adopted tactics depends on how well the players apply it. Players are the once that take part in the action and are responsible to give a better performance.

It should be so that when players notice their tactics not working, the managers attention should be drawn inorder to change to a more suiting formation. Then again, it all comes done to how the players perform with the changes too