I'm not saying the O's would have beat whomever they had faced in the playoffs but I think it's extremely likely that the Rangers don't make the playoffs without Montgomery. I like the O's chances better against whatever team they would have faced over the Rangers team that swept them.
To say that the O's scored one run is pretty meaningless, since, butterfly effect, they wouldn't have been facing the Rangers.
This is obviously with hindsight. It didn't take a crystal ball to see that more could have been done over what was done.