The 28-year-old Santos, who recently inked a three-year deal with the White Sox, went 4-5 with 30 saves and a 3.55 ERA in 63 games last season for the White Sox. His 92 strikeouts ranked second among American League relief pitchers.
Toronto was expected to be active in the closer's market, but was wary of high-priced options like Ryan Madson and Francisco Rodriguez. In Santos, the Blue Jays get a pitcher who could be under their control through the 2017 season.
Under the terms of Santos' recent agreement, he will receive $1 million in 2012, $2.75 million in 2013 and $3.75 million in 2014. The Blue Jays now hold a $6-million club option in 2015, an $8-million option in 2016 and an $8.75-million option in 2017. Santos will receive a $750,000 buyout payment if any of the three club options are declined by the club.
The 6-foot-2, 230-pound Santos is 6-7 with 31 saves and a 3.29 ERA in 119 relief appearances over two seasons with the White Sox.
Molina, 22, was one of the top pitching prospects in the Jays' system. He appeared in 26 games (23 starts) in the minors last season and was 12-3 with a 2.21 ERA with 148 strikeouts in 130 1/3 innings. The hard-throwing hurler made five starts at the Double-A level and was 2-0, surrendering just one earned run in 22 innings, while striking out 33.