Is it addition by subtraction or subtraction by addition?

Mike Pelfrey agrees to terms on a one-year contract. 
Rich Harden signed as a free agent.
Steven Hirschfeld was released.
Clint Dempster was released.
Ricky Bowen was released.
Wang-wei Lin was released.
Corey Kimes was released.
Jacob Younis was released.

Mlb.com lists the following players as "assigned to the Minnesota Twins". I don’t really know what that means—spring training invitations, maybe? Anyway, here’s the list: Nick Blackburn, Chris Colabello, Kyle Knudson, Danny Lehmann, Dan Rohlfing, Anthony Slama, Mark Sobolewski.