Possible Clues:

• He hit his 600th homer 6/20/2007
• Diamond-dominating Dominican
• National League's MVP of 1998
• 1998 MVP slugger
• "Slammin' Sammy"
• Sammy with over 600 homers
• MVP slugger of 1998
• Big Cub
• Member of the 500 home run club
• Chicago slugger