I remember some good stories after the last MAX scandal, like https://qz.com/1776080/how-the-mcdonnell-douglas-boeing-merg.... It's not clear whether Stonecipher simply outmaneuvered Condit, or perhaps McDonnell Douglas execs were knowingly elevated because Condit didn't trust others, who might also have resented his decisons.
Interesting article: "An ambitious program of cost-cutting, outsourcing, and digitalization had already begun (before the merger)". It seems like Boeing may wanted MD executives "expertise" at cost-cutting based management.