This article is part of our Rising Star Portfolios series.

I've already made one purchase of Madison Square Garden (Nasdaq: MSG) shares. Now I'm back for another chunk.

Why? The Knicks landed Carmelo Anthony, after weeks of high drama that would make a telenovela look tame. 'Melo inked a three-year, $65 million extension with the New York basketball team, which Madison Square Garden conveniently owns. The move makes the company more attractive, so I'm adding shares to my Special Situation portfolio.

Having superstar players can be especially valuable for Madison Square Garden, which was spun off a year ago from parent Cablevision (NYSE: CVC). Anthony's debut for the Knicks saw the MSG network – owned by the same parent – score its highest rating for a regular-season Knicks game in 16 years, quadrupling this year's average viewership. Such high ratings indicate that the superstar can make Madison Square Garden's media network more valuable, even if ratings are not at record levels every game night. Still, the Miami Heat, which scored LeBron James in the offseason, has seen a doubling of local ratings so far this season.

In addition, Anthony's presence increases the value of the team, which was already rated by Forbes as the most valuable NBA franchise, worth $655 million. In contrast, LeBron James's departure from the Cleveland Cavaliers last year sunk the value of that team by 26%, according to Forbes.

If Carmelo can help lead the Knicks deep into the playoffs, he could really provide another revenue driver to a stock that already has several, as I detail in my original buy decision. So with the arrival of 'Melo and the undervalued nature of the stock, I'm doubling down on shares of Madison Square Garden, adding another 3%, or $500, to my Special Situations portfolio.

Interested in other media stocks? Here's one that I call free money.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.