"I am trying to reconcile this with getting someone to who is under-performing to step up. You can be kind, up to a point. Sometimes you need to be direct in a calm, professional manner."

I think there's a difference between being kind and being wishy-washy. From what I'm reading, DJ always has a goal (complete this raid with this group, train this player, make this guy not feel like a heel for leaving suddenly because his kid just puked all over the floor) and he's always moving toward that goal with the added challenge of doing it without being a dick. What would DJ do when presented with a straight-up griefer? I imagine he would act, without malice or meanness, but effectively, to protect the experience of the people who are truly into it. In the same way, kindness in managing employees may lie in getting somebody to recognize that their time is best spent doing not-what-they've-been-doing (see the example in a previous Rands article I forget where he said this very thing).