Conversation so far:
What happened to Martin Kaymer in 2011?
Entering the 2011 season, Martin Kaymer turned down a chance to become a full PGA Tour member.
What did Martin Kaymer do instead of becoming a full PGA tour member?
Martin Kaymer had gained exempt status with his win in the PGA Championship. He stated he would concentrate on the European Tour for 2011.
Which tournaments did Martin Kaymer play in Europe?
Martin Kaymer participated in several, including the Madeira Islands Open in Portugal and the BMW International Open in Germany.
Which tournaments did Martin Kaymer win in 2011?
Martin Kaymer won the Abu Dhabi HSBC Golf Championship and the WGC-HSBC Champions event in China.
Did Martin Kaymer have any problems in 2011?
Martin Kaymer decided to undergo a swing change to be able to move the ball both ways, but later decided that was a big mistake.

Question: How did he become the number one ranked palyer?
Self-contained rewrite: How did Martin Kaymer become the number one ranked player?