Catchers Luke Maile and Curt Casali highlighted the players optioned to Minor League camp, along with right-hander Ryan Garton.
Left-hander Justin Marks, right-hander Diego Moreno, catcher Michael McKenry and outfielder Shane Peterson were reassigned to the Minors.
That leaves 34 players in camp, with five likely headed to the disabled list, including shortstop Matt Duffy, outfielder Colby Rasmus, catcher Wilson Ramos and right-handers Shawn Tolleson and Brad Boxberger.
Maile told reporters he didn't take the news well.