Transformational leadership builds on transactional leadership, adding to what it achieves for performance, effort and satisfaction; it does not replace it. Constructive and especially corrective transactions have only marginal effect unless joined by a transformational component: the follower needs to feel valued, to find meaning in the work and to have a sense of ownership. Consistently honoured transactions build the trust on which transformational leadership stands, and the most effective leaders balance the two across time, situations and challenges, with more of the transformational. Because the two orientations involve different mind-sets, a purely transactional leader cannot move up the range by adding behaviours alone; development has to change how the leader thinks about the task (its larger meaning, the development of the people doing it, the assumptions to challenge, the ethics not to compromise).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.