In business, when a company wins a contract they usually have mixed feelings. They're happy that they won the contract. But they also realize that they probably overpaid for it. This would certainly be the case if the Cubs were only bidding on Maddux's pitching abilities.
The details are not yet public, but the Cubs have paid $7.5 million+ for a fifth starter in their rotation. Maddux had his worst year since 1987 and his numbers will probably continue to fall over the next two years. I doubt any other teams were seriously considering signing Maddux for this amount.
However, this is not a bad investment for the Cubs. Even though he left the Cubs high and dry over a decade ago, Maddux remained popular with Cubs fans. And while Wrigley would have remained at capacity with or without Maddux this year, the Tribune Company will be able to recoup their investment through higher television ratings and advertising dollars. Maddux going for his 300th win will be icing on the cake.
So this move actually makes perfect business sense. Assets should be employed by the companies to which they have the most value. And Maddux adds more value to the Cubs than any other baseball organization.