The Chicago Cubs are flying. Now maybe the sale of the team finally will, too.

After months of delays in Tribune Co. Chairman Sam Zell's year-old plan to sell baseball's lovable losers, briefing books with confidential financial information on the team were sent to prospective buyers Tuesday, Cubs Chairman Crane Kenney said in an interview. Now, the question is whether the team's atypical league-leading performance so far this season can offset a tight credit market. Also problematic could be Mr. Zell's plan to separate the team from its stadium in the sale. If successful, experts say it could be baseball's first billion-dollar transaction.