Complex sentence: Since then Hawthorne hasn't missed a tournament, reaching the quarter finals 28 times but only once advancing to the semi-finals, which was at the Kansas City Pro-Am in September 2011, when he lost to Kane Waselenchuk in three games.
Split into simpler sentences: Since then Hawthorne hasn't missed a tournament., reaching the quarter finals 28 times but only once advancing to the semi-finals. That semi-final appearance was at the Kansas City Pro-Am in September 2011, when he lost to Kane Waselenchuk in three games.