Hmm - as someone who has been on the receiving end (having to review the essays) I may be able to provide insight. Although there may be a set of criteria that are used to rank each entry, it all comes down to the subjective opinions of the reviewers. It is a multi-stage process, gradually weeding out until the top entries are selected - and you ended up in that top group. Afterward, they sort out the "top of the top". Chances are, the majority of them will have exactly the same subjective score (after all, there were 320 of them to begin with) ... so the reviewers re-rate them. At this point, the original criteria are a moot point. You probably received that "very close to perfect" score because they didn't like yours as much as some of the others. It's pretty much a crap shoot - at any other time, yours may have made the top pile also.
So - don't feel bad. You could have submitted War and Peace and it wouldn't have made any difference if the raters didn't "like" it as much as the others. This year, maybe you should include verbiage about how many times you have submitted applications.. persistence is always an admirable quality. Keep on trying, I am sure your luck will improve .