Calderon is too good to be a 10-12 minute a night backup. Only a 6-8 minute a night guy in the playoffs. He needs the ball in his hands offensively to have value. To run the offense. Otherwise, he is basically Steve Blake. Calderon doesn't add value as a two guard playing off the ball. His limitations as a defender/rebounder take more off the table than his largely one dimensional (when off the ball) offensive game adds (large net negative as SG). Consequently, both Bass and Lee offer more value to Boston than Calderon does. There just isn't a role big enough here for Calderon to succeed.
The Raptors have no use for Bass or Lee. Both players would be seen as having negative trade value due to their contracts. The Raptors have Bargnani, Ed Davis and then Amir Johnson at power forward. At shooting guard, they have DeMar DeRozan, Terrence Ross and Alan Anderson. They have no need for Lee or Bass. They are just dead weight on their salary cap.
Both Boston and Toronto would get worse with this trade.