The comic and Emmy Award-winning sitcom star, 45, is filming Mr. 3000, the story of a major leaguer who retires thinking he has 3,000 hits, only to return 10 years later when he learns he's still three hits short.
SI: Give us a preview of your character in Mr. 3000.
Mac: Stan Ross is a very confident, over-the-top, self-centered, egotistical, arrogant son of a bitch. The only thing he cares about is himself. But he can swing the bat, and he's got pizzazz.
SI: Have you based your portrayal on any real-life major leaguer?
Mac: No. I wanted to individualize this. The only thing I might have taken in terms of hitting was Roberto Clemente, because he was my idol. I'm a fan of Ichiro now. He and Clemente have the same style: They play rightfield, they have the dynamite arm and they come to play all the time.
SI: Has anyone worked with you on your swing?
Mac: We train with coaches and we soft toss and hit BP. They're right there on the set watching us. [Former major league pitcher] Bill Landrum is a pitching coach, and he's been burning us out. He throws hard sliders.
SI: You grew up in Chicago. What's it like being a fan of Chicago sports teams?
Mac: We're disappointed. The Bears? One Super Bowl, 1986. How in the hell you win only one championship with that team? Chicago sports beat us down. I'll give you an example. How the hell do the Bulls get rid of Jordan, Pippen, Phil Jackson, Horace Grant, a championship team that dominated the 1990s? In Chicago, we're suckers.
SI: In the 1970s and '80s, you played semipro basketball. How was your game?