CREATE TABLE table_38988 ("Round" FLOAT, "Pick #" FLOAT, "Overall" FLOAT, "Name" TEXT, "Position" TEXT, "College" TEXT)

What round on average was a defensive tackle selected?
SELECT AVG("Round") FROM table_38988 WHERE "Position" = 'defensive tackle'
SELECT AVG("Round") FROM "table_38988" WHERE "Position" = 'defensive tackle'