But it is your job to figure out why you got unmotivated people.
* Is your hiring process borked?
* Is there something wrong inside your organisation that's regularly breaking motivated people?
… and so on …
Terrible management and/or micromanagement is one of the key reasons a dev can lose motivation. It also doesn't do anyone's morale/motivation any favors to see colleagues get fired. If a manager has had to fire people, and do so repeatedly, then the fault is not so much with those getting fired than the organization/management/hiring process.
One of the key reasons why I've seen dev lose motivation after joining a company is lack of investment on the part of the manager in the employees future goals. I've been in situations during my entry-level days when my manager always made me draw the short straw - did wonders for my motivation.
Also some management people have completely unrealistic expectations from a hire whose job they hardly understand and with whom they never really talked openly.