You're ignoring the fact you listed Dickey, Bonifacio (who's had 3.0 WAR and 2.1 WAR season), Izturis (who was consistently above replacement level as a part time player throughout his career) and Esmil Rogers, who actually wasn't below replacement level in 137 innings in 2013.
Anyway - I agree, Colabello sucks. He's turned back into a pumpkin and should never have been in LF to start with. My point is it's easy even look at successful teams and cherry pick decisions they have made. I don't fault the Jays organization for giving Dickey, Boni or Izturis an opportunity. I also don't fault them for giving some of their better prospects a chance at the ML level (2012 Drabek, 2013 JPA, Sanchez).
That narrows it down to Laffey, McGowan, Goins and Colabello. All of them are 25th roster guys - these things happen. Colabello's still at a wRC+ of 143 on the year - I don't have an issue with him getting some PA's at DH.