MLS. By 2008, San Jose had returned to the league under new ownership, and in 2009, the expansion side Seattle Sounders FC began play in MLS. The Sounders set a new average attendance record for the league, with 30,943 spectators per match, and were the first expansion team to qualify for the playoffs since 1998. The 2010 season ushered in an expansion franchise in the Philadelphia Union and their new PPL Park stadium (now known as Subaru Park). The 2010 season also brought the opening of the New York Red Bulls' soccer-specific stadium, Red Bull Arena, and the debut of French striker Thierry Henry. The 2011 season brought further expansion with the addition of the Vancouver Whitecaps FC, the second Canadian MLS franchise, and the Portland Timbers. Real Salt Lake reached the finals of the 2010–11 CONCACAF Champions League. During the 2011 season, the Galaxy signed another international star in Republic of Ireland all-time leading goalscorer Robbie Keane. MLS drew an average attendance of 17,872 in 2011, higher than the average attendances of the NBA and NHL. In 2012, the Montreal Impact became the league's 19th franchise and the third in Canada, and made their home debut in front of a crowd of 58,912, while the New York Red Bulls added Australian all-time leading goalscorer Tim Cahill. Expansion of the league With an average attendance of over 20,000 per game, MLS has the third highest average attendance of any sports league in the U.S. after the National Football League (NFL) and Major League Baseball (MLB), and is the seventh highest attended professional soccer league worldwide . In 2013, MLS introduced New York City FC as its 20th team, and Orlando City Soccer Club as its 21st team, both of which would begin playing in 2015. In 2013, the league implemented its "Core Players" initiative, allowing teams to retain key players using retention funds instead of losing the players to foreign leagues. Among the first high-profile players re-signed in 2013 using retention funds were U.S. national team regulars Graham Zusi and Matt Besler. Beginning in summer of 2013 and continuing in the run up to the 2014 World Cup, MLS began signing U.S. stars based abroad, including Clint Dempsey, Jermaine Jones, and Michael Bradley from Europe; and DaMarcus Beasley from Mexico's Liga MX. By the 2014 season, fifteen of the nineteen MLS head coaches had previously played in MLS. By 2013,