Who will be this year's Zach Duke? An early candidate: Chicago's Sean Marshall. A year ago the lefty was pitching for Single A Daytona. Today he's being counted on to help bring stability to a struggling rotation. Marshall is a towering 6-foot-7 but isn't a power pitcher like his twin brother, Brian, also selected by the Cubs in the 2003 draft. Marshall, who reminds scouts of Mark Mulder, possesses excellent command of his low-90-mph tumbling fastball and should be frustrating opposing hitters at Wrigley for years to come.