What is the pick number average for the player who was drafted before round 7, and went to college at Tennessee?
CREATE TABLE "2002_nfl_draft" (
  "round" real,
  "pick_num" real,
  "overall" real,
  "name" text,
  "position" text,
  "college" text
);
SELECT AVG("pick_num") FROM "2002_nfl_draft" WHERE "round"<7 AND "college"='tennessee';