Only one goalkeeper has ever won the Ballon d'Or in the award's history. Lev Yashin, perhaps the greatest keeper in the history of the sport won the award in 1963.
However, if there is ever going to be a keeper to match this feat it will be Spain's Iker Casillas who had a monumental 2012. He won the La Liga championship in the 2011-12 season with 41 wins, 20 clean sheets and over 4700 minutes played. He also made a decisive save on Xavi at the Camp Nou in a 2-1 win that essentially sealed the title for Madrid. He also made two crucial saves against Bayern Munich in the penalty shootout at the Champions League semi-final. (Cristiano Ronaldo, who is widely believed to be a major contender missed his shot).
On the international front he scored the Euro Cup 2012 by allowing just one goal and setting a new record for most minutes without allowing a goal in history. That streak was extended over two World Cup Qualifiers before France finally ended it in the final moments. The shutout streak is not the only number worthy of mention however. Casillas made several huge saves for Spain on route to winning the Euro including saves in the decisive penalty shots against Portugal in the semi-final and a huge save against Croatia that could have eliminated Spain from the group stage. He also became the first keeper in history to win 100 matches with their national team when he shutout Italy in the Euro Cup final.
He was also awarded the Prince of Asturias award along with Xavi . The award is given to people or organizations that have made major impacts in the world.
Biggest Moment of the Year: Too many to count. The Spanish League Championship was the first for Real Madrid since 2008 and the Euro 2012 championship made Spain the first international side to win three straight major tournaments in a row.
Chances of Filling the Final Spot in the Top 3: Excellent actually. He has been backed by a number of major figures including Spain's prime minister and soccer legend Pele. He has done something that neither Messi or Ronaldo have accomplished all season and is one of just three players on the entire list (Sergio Ramos and Xabi Alonso being the others) to have won both the Euro 2012 and the Spanish League Championship. It also helps that he is the captain on both sides and has proven to be a strong leader that owns up to his responsibilities.