It is sad that being an engineering manager in the vast majority of tech companies is about politics not about engineering. A lot of engineers who opt for the management root learn this the very hard way.
The big persuasion missing from the list is persuading, both upwards and downwards, who should work on what.
It sounds super cynical but it is important to park the unproductive people on the unimportant work else nothing works. It is usually counterproductive to actually release people (the EM is rewarded for number of reports above all else) etc so you have to put the good people on what is important and somehow lend the bad people to the projects and competing teams to hamper them etc.
Sad but super true.