Let consciousness be the 'neutral' condition. Then concentration would be non-neutral, or active. It is that state of consciousness that has a focus. And specifically, it is focus-with-intent.
To my mind, concentration is that focus of mind we adopt whenever we wish to effect either an action or a state of being. And since there is no time (or space) we should not think of this as a 'doing'. Rather, it is an active choice or willingness to choose a particular direction.
So concentration is that state of being that concerns itself with which sliver pathways one wishes to aim for.