During his career, Nelson has received several postseason assignments, including the 2005 World Series, 2009 World Series, 2014 World Series and the 2018 World Series. He also worked the League Championship Series in 2002, 2004, 2010, 2011, 2012, 2015, 2016, 2019 and 2020; and the Division Series in 2000, 2001, 2005, 2008, 2009, 2014, 2017 and 2018. Nelson has also umpired in the 2006 and 2014 MLB All-Star Games.