And they're apparently pretty approximate, if being 'disengaged' means that you're only 18% less productive than your 'engaged' coworkers. And then they provide the striking statistic that it will cost an employer up to 2X the annual salary of the 'disengaged' worker to replace them - that's equivalent to ten years of their not working hard, doesn't seem worth it, somehow.
Totally agree, the numbers in this article strike me as ranging from "suspect" to "bullshit". I should've clarified that I was defining how I and (I think) other real managers use those terms.
For example, my guess would be that the lost value from a disengaged employee is closer to 100% of their salary than 18%, because of how they drag the rest of the team down by generating bugs, derailing conversations, needing constant help to un-fuck their local env, etc.