A 1987 Minnesota Twins Team Signed Baseball with the key signatures: Hrbek, Puckett, Viola, Blyleven, and Carlton is worth about $300.-$400. A 1987 St. Louis Cardinals Team Signed Baseball with the key signatures: Smith, and McGee is worth about $175.-$250. Value is based on average prices of recently closed auctions. Prices may vary based on condition, and the type of authenticity that accompanies the baseball. Prices may also vary based on the amount of signatures, and key signatures acquired. The more complete the baseball with key signatures the more valuable. If the signatures are not properly authenticated the baseball could sell at half the market value or less. If the baseball has the signatures of players from both teams It will have a lower value.