What is the mean pick when the play is Marc Lewis (lhp) and the round is less than 20?
CREATE TABLE "players_selected" (
  "round" real,
  "pick" real,
  "player" text,
  "nationality" text,
  "school" text
);
SELECT AVG("pick") FROM "players_selected" WHERE "player"='marc lewis (lhp)' AND "round"<20;