Once again, he has a 2.30 ERA since May 8th. Robertson doesn't have to pitch better than he has most of the year, he just has to keep pitching like he has for the majority of the season. I'm forced to believe, at this point, that you're simply not reading my posts.
They also don't need Hughes to transition seamlessly to the bullpen, they would just need him to be serviceable. Also, Aceves might be back at some point, which would be a boost.
But again, in the playoffs, they can ask Rivera to get six outs. Conceivably, if just one other reliever steps up, they should be OK.