For the four major leaguers who were in his midst this winter — Matt Holliday and Bobby Crosby of the Athletics, and Chris Duncan and Skip Schumaker of the Cardinals —McGwire’s guidance was like a cross between fantasy camp and physics class. "You walk up and it’s Mark McGwire, of all guys, teaching you how to hit," Schumaker said last week. "You think he’s just so big and strong and that’s why he hit home runs. But he really knew what he was doing at the plate." McGwire was just as enthused as he discussed the collaboration. "It was really cool that Matt called and said, ‘Let’s work together,’ " McGwire said of Holliday. "Next thing you know we’re working with Bobby and Skip, too."