Okay, so the Astros acquired the following players today (alphabetically);
Joe Biagini
Zack Greinke
Martin Maldonado
Rainier Rivas
Aaron Sanchez
Cal Stevenson
Raider Uceta
They also traded the following players away (alphabetically)
Seth Beer
J.B. Bukauskas
Derek Fisher (40-Man)
Corbin Martin (40-Man)
Josh Rojas
Max Stassi (Active & 40-Man)
How does the Active Roster / 40-Man Roster fit with all of this going on?
First off, you do not need to put Rivas, Stevenson, or Uceta on the 40-Man Roster. So the Astros cleared one spot on the Active Roster (Stassi) and three spots on the 40-Man Roster (Stassi, Fisher, Martin).