Gilbert Arenas is back in the NBA, officially signing Tuesday with the Memphis Grizzlies. Released under the amnesty clause in December – and still due more than $60 million from the Orlando Magic – Arenas worked out for the Grizzlies on Monday. The Memphis Commercial-Appeal reported that Arenas appeared slender and shot the ball well during the workout. The Grizzlies could use Arenas’ shooting ability as they are next to last in the NBA with 3.8 3-pointers per game. Arenas also can