Fiers is very good. 3.1 fWAR and a 3.12 ERA in his last 178.2 major league innings (2014-2015).
If the rumour is true, and it seems plausible, then I think you can count Toronto out for all of the big rentals. They are probably looking at more controllable players without big 2015 salaries.
Non-Rental Targets
Tyson Ross - $5.2M salary - controllable through 2017.
Jesse Chavez - $2.2M salary - controllable through 2016.
Andrew Cashner - $4M salary - controllable through 2016.
Jon Niese - $7M salary - controllable through 2018 (two team options).
The list isn't very long though. Hard to find guys that fit the bill.
Shields and Hamels - controllable BUT expensive.
Jose Quintana and Alex Wood - controllable BUT expensive in terms of prospects.
Gallardo, Haren, Colon, Leake - Not controllable, particularly sexy, or cheap in terms of $$, but wouldn't cost a very good prospect.