I heard from another playwright that a lot of the time people who are doing the first pass on applications are current grad students. Not sure how true it is, but in my experience as a literary journal editor, I can tell you that people get rejected for all kinds of reasons. The person reading your application might just have been in a bad mood, or hungry, or have a personal issue with your style. Maybe they were really on the fence about your play and agonized over the decision but ultimately felt another one was better. Maybe someone on the committee really loved your work and was pushing for you, but they got overruled (I've had to reject lots of pieces I loved because other editors disagreed with me). Or maybe they didn't feel like you'd fit in well with the cohort they were building. There are all kinds of reasons for a good application to be rejected, especially with programs that are as competitive as this one. Rejections suck but they are absolutely not a referendum on your work as a whole.