Vehemently disagree with this comparison.
I'm not here to defend Jabari's D but his problems are more tangible, its lateral quickness on the perimeter and lack of strength in the post mixed in with some confusion in P+R and some questionable effort. simply put Jabari gets beat by lesser players
Harden on the otherhand beats himself, hes not even paying attention most of the time and appears totally in his own world, a liability at any given moment.
https://www.youtube.com/watch?v=wVYJULACcao
https://vine.co/v/MnTZY1Pq11F <-- harden having a lapse last night during crunch time... wtf is he thinking, its almost like he doesn't have the attention span for defense