What division did the Nashville Metros play in during the year that they did not qualify for the Playoffs, where in the USL PDL League, and had the Regular Season 7th, Southeast?
CREATE TABLE "year_by_year" (
  "year" real,
  "division" text,
  "league" text,
  "regular_season" text,
  "playoffs" text,
  "open_cup" text
);
SELECT "division" FROM "year_by_year" WHERE "playoffs"='did not qualify' AND "league"='usl pdl' AND "regular_season"='7th, southeast';