Case has cutoff for every section of the DAT and I guess it's at least 18-19 in every section .......not sure about the math section thou but sure about others.
Every school is different. GL.
When were all of your materials in to Case? They do things very quickly. I think they started giving out interviews in like July maybe, so if your app wasn't in early, it doesn't mean you aren't a good candidate, but I'm pretty sure by now their interviews for the year are all filled up or almost filled up. It's unfortunate, but I guess that's kinda how the rolling admissions process works.
Each school starts looking at things at different times. Case is probably one of the earliest, and I know some schools just started giving out interviews recently or will be soon. Don't get too worried!