The role of the President has been somewhat mythicized over time, think George Washington and his cherry tree. But this legacy does not spur from nowhere. Individual Presidents have had a marked role in setting the tone of the Presidency, in passing policy that would affect the nation for years to come, and in changing how we view Presidential power.
That is in no way to say that the role of Congress, of events, of public opinion have no role. Each of these play a significant part in the success or failure of any administration. But the person who occupies the seat of the Presidency also plays a part. The major critique against this thinking is that it is easy to have a scapegoat when the administration steps wrong or when the public is unhappy. In this way we equate visibility with importance and inflate the role that the person plays with the power of the branch of government. While the President is an easy figurehead to blame, this does not mean that the President as a person is without reproach in these scenarios.
The President has significant power in choosing staff, negotiating with allies, setting up agencies and institutions, pushing legislation that will be debated, signing and vetoing and passing executive orders. All of these play significant roles in the overall shape that an administration will take. Outside circumstances may force a President to deal with a crisis or to shift agenda priorities, but the President is impugned with the power to make the checklist of what will be accomplished or at least attempted.
In times of crises, moments that have the potential to shape not just the Presidents legacy, but the future of the country, these decisions often come down to the President. Of course, there are advisors, councils and agencies that inform all possible routes but when many of these decisions are uncertain, it comes down to Presidential decision making.
While there are many variables that should be examined when looking for patterns of success or failure. We cannot discredit the character and personality of the President when making associations. President George Washington set a precedent for the peaceful transition of power which has remained despite violent protests like we have seen recently. This was not directly implied in the Constitution or in any other institutional patterns. His character, charisma and personality informed and set the mold for what the office of the President would look like. In this same way, many other Presidents have expanded on this role and seen success and failure by their own work.