Exactly, BJCP judging is more art than science.
There are so many factors that go into it - how was your bottle handled during shipping? How was it stored before the comp? When was it opened? How was the pour? How long did it sit in the glass? What temp was it stored at? What temp was it poured at? What temp was it tasted at? What place was it in the flight? What are the judges experience levels? What are the judges tasting preferences? Etc. Etc. Etc.
Remember, BJCP comps are there to tell you that you're beer is great. They're there, in part, to tell you the finer points of how your beer doesn't meet the style. We've gone soft as a society when it comes to criticism.
I entered several beers, meads, and ciders in the AZ, NHC, and Mazer Cup comps because they are all held around the same time (multiple judging on the same batches). The variety of scores and comments were......shall I say, interesting.
That's part of the fun of competitions, in my opinion.