My cavil with Team of Rivals is that it was commonplace in early US history for ambitous politicians to serve in the cabinet on their way to the White House, or prior to an unsuccessful attempt(s) to be elected president. Most of us know, for example, that Thomas Jefferson served in Washington's cabinet. Many of us also know that presidential wannabes like Clay and Calhoun served in the cabinet. Lincoln's predecessor, Buchanan, has been in the cabinet under President Polk.
What was not commonplace about Lincoln's cabinet was that it was a war cabinet in the most cataclysmic military conflict in US history. There was therefore a sense of urgency and purpose that overrode a lot of the petty political bullxxxx that characterized the progress of so many of the earlier cabinets.