I think the difference between this and Oh Mary is that Oh Mary deals with outsized emotions and broader comedy, which both translate decently well to a slightly bigger stage, not to mention that there just aren't that many comedic plays currently running.
Job on the other hand is a small show that deals with the nuances in two people's interactions. And though it was sold out in both of its off Broadway runs, I never heard the same buzz around it as Oh Mary, which had reached beyond the circle of just theater people (at least for me it had). And Oh Mary has done some smart promotion, whereas I'm not too sure what if any marketing Job has really done, outside of sending discount codes to mailing lists of people who have already seen the show.
I also thought it was fairly telling that so many people on this board liked the show but mentioned they wouldn't necessarily want to see it again. I definitely walked out of it wanting to give it another watch after seeing it at SoHo Playhouse, so I'm not sure if it's just that other people in general liked it less, or if there's something about the intimacy of a smaller venue that makes it feel less gripping (Theatermania essentially said as much in their review)