I'm not sure the NL doing that would be as benefical as it would be in the AL due to the P spot coming up right before the leadoff spot and that P spot kills many innings and could allow them to pitch around Harper in the important situations.
With 1 out, you pitch to the P spot get to 2 outs and walk Harper. With 0 out, you pitch to the P spot, get the out, and walk Harper to set up DP. With 2 out, you just get the P spot out and Harper starts the next inning with nobody on base.
I guess that assumes it's the P hitting, which in late game scenarios it would likely be a pinch hitter instead. ...