Ex-Chelsea midfielder Michael Ballack has re-signed for former club Bayer Leverkusen on a two-year deal.The 33-year-old German, who missed the World Cup because of an injury picked up in the FA Cup final, was released by Chelsea at the end of last season.He reached the Champions League final with German side Leverkusen in 2002. With my transfer a circle is complete.I had a beautiful and successfu