Johnson, 30, had surgery in October to clean a bone spur out of his elbow. He also missed more than three months with a forearm strain and triceps inflammation last season. Johnson's list of arm injuries is pretty long, and it includes Tommy John surgery (2007) and a serious shoulder strain (2011).
In 16 starts and 81 1/3 innings for the Blue Jays last season, Johnson went 2-8 with a 6.20 ERA (66 ERA+) and 1.66 WHIP. He did manage to throw 191 1/3 innings with the Marlins in 2012 (107 ERA+), but was limited to only 60 1/3 innings in 2011.
With Johnson out, left-hander Robbie Erlin figures to join Andrew Cashner, Ian Kennedy, Tyson Ross and Eric Stults in the San Diego rotation.
The Padres signed Johnson to a one-year, $8 million contract this offseason. If he makes fewer than seven starts in 2014, the team gets a $4 million club option for 2015.