Free-agent guard Joe Johnson is returning to the NBA after a three-year absence and at age 40, as he is signing a 10-day contract with the Celtics and is expected to play Wednesday, sources told ESPN.Free-agent guard Joe Johnson is returning to the NBA after a three-year absence and at age 40, as he is signing a 10-day contract with the Celtics and is expected to play Wednesday, sources told ESPN.Read More