In the long run of history, where a President is in the order of attaining the Presidency really matters.
So, for instance, John Adams is between George Washington and Thomas Jefferson, and while Adams ranks around the middle in ranking of Presidents by historians and political scientists, he is rated much lower than the two Presidents before and after him, who are in the top ten of any listing.
The same goes for William Howard Taft, who is between Theodore Roosevelt and Woodrow Wilson, both of whom are in the top quarter of Presidents, while Taft is rated in the mid 20s.
And the same is true for George H. W. Bush, who is between Ronald Reagan and Bill Clinton, both of whom are rated higher than Bush, who is rated in the later teens as President.
On the other hand, Abraham Lincoln comes between the two men usually rated the two worst Presidents, James Buchanan before him and Andrew Johnson after him.
And it is now clear that Barack Obama, rated 11th in one poll, 8th in another poll, and 17th in a third poll, all within the two years he has been out of the Presidency, is fortunate to have George W. Bush, rated in the 30s, and Donald Trump rated either at the bottom under Buchanan and Andrew Johnson, or at most just above them, insuring he will, like Lincoln, always be rated much better.