alexander played little league baseball and attended cardinal newman high school in santa rosa, california, where he was named the north bay league player of the year as a senior. he set the school records for strikeouts in a season and a career and led them to the league championship in 2007. he was drafted by the cincinnati reds in the 37th round of the 2007 major league baseball draft but did not sign and instead attended pepperdine university to play college baseball. he was selected to the all-west coast conference freshman team in 2008 when he was 7–4 with a 4.95 era and struck out 106 batters. he was 4–5 with a 4.11 era as a sophomore, when he was used as both a starter and a reliever. between his two seasons at pepperdine he played for the la crosse loggers of the northwoods league. after the 2009 season, he played collegiate summer baseball with the brewster whitecaps of the cape cod baseball league.