After an impressive preseason, Cooper Rush earned a spot on the Cowboys roster.Sunday against the San Francisco 49ers, Rush was active as Dallas' No. 2 quarterback behind Dak Prescott, according to radio analyst Babe Laufenberg.Rush hasn't been active for any of the first five games. The Cowboys have been keep two quarterbacks active on game day and they've been going with veteran Kellen Moore behind Dak Prescott.