The English Premier League is arguably the world's most popular sports organization, and this season saw explosive growth off the pitch in the realm of social media.

Manchester City snagged its first English title in 44 years last weekend to cap off another dramatic EPL season. To recap how the league developed digitally this year, Mashable hunted down some stats. We also consulted Sean Walsh, whose blog Digital Football is a leading source on the intersection between English soccer and social media.

"EPL clubs have been criticized in the past for their out-of-date approach to social media in comparison to the youthful and creative tactics employed by U.S. franchises in the NBA and NFL," Walsh, who's interviewed the digital directors of several top European clubs over the past year, told Mashable in an email. "But the 2011-2012 season has seen the rise of social media in 'the beautiful game,' and Premier League clubs have finally begun to invest in it."

Walsh says EPL clubs added a total of more than 17 million Facebook fans over the course of the season. In total, the league has almost 60 million Facebook likes — all the more impressive when you consider England's total population is just over 50 million people.

So far, both the league and its individual teams have a much stronger presence on Facebook than on Twitter, where clubs count a combined following of less than 4.5 million. But the EPL's presence is growing rapidly on Twitter as well as Facebook — Walsh counts a 126% increase in followers league-wide since last season.

Premier League side Chelsea was also involved in a piece of Twitter history recently. Its win over FC Barcelona in last month's Champions League semifinal set a Twitter sports record of 13,684 tweets per second, eclipsing the previous record set by the most recent Super Bowl. Chelsea takes on Bayern Munich in the Champions League final this Saturday, so we'll see if it can make Twitter history again.

Liverpool, meanwhile, became the first Premier League team to promote itself using Pinterest. The team stocked boards with historic photos, fan gear, old uniformas and memorabilia. Pinterest has become one of the newest ways sports teams around the world are seeking to leverage social media.

Among Walsh's favorite individual digital EPL moments this year: Manchester City launching a YouTube partnership taking steps toward integrating fans' in-person and social media experiences; Queens Park Rangers owner Tony Fernandes using Twitter to ask fans which players they wanted the club to acquire; and midfielder Joey Barton using promoted tweets to apologize to fans for being thrown out of a match.

How do you think English soccer stacks up to other pro sports in leveraging social media? Let us know in the comments.

Image courtesy toksuede, Flickr.