Yesterday, sports blog Deadspin exposed confidential financial documents for a number of baseball teams, including the Seattle Mariners. All teams are privately held, so this kind of data is rarely seen. Which makes it difficult to know if an owner is making any money. Or whether you can trust his insistence that he’s not getting a return on his investment. So what did we learn about the Mariners?Well, most importantly, we found out what a difference a year can make. In 2007, the M’s took in over $17 million in net income. A year later that number had plummeted to a loss of $4.5 million.”Such variation is not unique to sports,” writes sports economist Craig Depken to Daily Weekly, “But is perhaps one of the reasons a team owner might ‘truthfully’ say that in a given year he/she lost money or barely made any money.”We also learned that the Mariners make bank off of their broadcasting rights. Bringing in more than $60 million each year. (For comparison’s sake, the Los Angeles Angels of Anaheim, who obviously play in a large market, made roughly $20 million less per year off of TV and radio rights.)Last but not least: based on this leaked data, we can surmise that Mariners fans stick by their team through thick and thin. In 2008 the Tampa Bay Rays went to the World Series. Yet the Mariners more than doubled the Rays in gate receipts (tickets sold), despite losing more than 100 games and playing a brand of baseball that would make the average fan’s eyes bleed.”This suggests that Mariners fans are probably rather loyal – that is, even when the team is not performing very well the fans still attend the games in a relatively (I stress that word) strong way,” writes Depken.Good thing too, considering this year’s squad is challenging that group for general suckitude and unwatchability.