2012 was Alfonso's first professional season, pitching for the Las Cruces Vaqueros of the Pecos League. Was an All-Star for the Vaqueros. Appeared in 32 games out of the bullpen, throwing 40 innings and holding a 4.05 ERA with a 5-0 record. Struck out 37 and allowed just 13 walks and three homers. Attended the University of Science and Arts of Oklahoma. Previously held the school record for appearances in a season with 26. Also attended Gateway Community College.