Herndon underwent Tommy John surgery in June. The 27-year-old made 97 appearances out of the Phillies' bullpen over the last three seasons, compiling a 3.85 ERA in the process. Toronto claimed him off waivers on Oct. 23 and designated him for assignment eight days later. He appeared in only five games for Philadelphia this season before injuring his right elbow.
A native of Victoria, Australia, Spence pitched in 51 contests for San Diego over the last two seasons. He posted a 2.73 ERA and tallied 31 strikeouts in 29 2/3 innings in 2011 and logged a 4.35 ERA in 11 outings during the 2012 campaign. The 24-year-old spent the majority of last season with Triple-A Tucson, for which he recorded a 4.20 ERA in 31 appearances.