Cubs outfield prospect Brett Jackson, who was promoted to Triple-A Iowa this month, is warming to the Pacific Coast League. In 67 games for Double-A Tennessee of the Southern League, Jackson hit .256/.373/.443 with 10 home runs and 32 RBI. He stole 15 bases and walked 45 times against 74 strikeouts. In five games for Triple-A Iowa, the Berkeley native is hitting .250/.375/.500 with an RBI and a stolen base. He is struggling with discipline, recording nine strikeouts against four walks in 24 plate appearances. Chicago drafted Jackson with 31st overall pick of the 2009 First-Year Player Draft out of the University of California. He has moved very quickly through the minor leagues and is considered top prospect in the team's system.