Erik Swanson
Full disclosure: it's not Swanson's fault that the results haven't been there for him this year. With a spring training that was cut short due to a serious accident involving his son, Swanson's head was nowhere near 'in the game' as the season got underway, which clearly led to a lapse in his mound performance.
However, he's going to fall into a similar category as Ryan Burr did above. The Blue Jays bullpen has literally been one of the very worst in all of baseball this year, and there's no reason they shouldn't move on from anyone who struggled and replace them on the free agent market. Swanson falls into that group despite the fact that he was one of the more reliable weapons in the 'pen last year.
Again, the Blue Jays simply cannot afford to keep a player like Swanson around if he's struggling so badly to regain his footing. He already had a(n unsuccessful) stint down in the minor leagues and things certainly did not get turned around. Instead, he was rushed back to the big leagues before he was ready for such a move.
In 34 outings this year, the 34-year-old has a 6.52 ERA, 7.39 FIP and 63 ERA+ in 29 innings. He's seen his strikeouts plummet, his walks raise at an alarming rate and his HR/9 spike by two full home runs. Looking at second-half performance alone, his 3.77 ERA is much better but his 6.81 FIP and 4.45 SIERA tell a story of luck rather than an improvement in his game.