Breslow's arrival forced the A's to make a roster move, and it was widely assumed that one of the team's seven relievers would be optioned to Triple-A Sacramento; righties Chris Schroder and Kevin Cameron were the logical candidates for demotion.
Instead, Oakland optioned outfielder Aaron Cunningham to Sacramento, leaving the A's with an eight-man bullpen and only two healthy backup position players.
Schroder was called up from Triple-A on Tuesday but did not pitch Tuesday or Wednesday. Cameron was recalled April 29 and had a 2.45 ERA in seven appearances through Wednesday.
Cunningham was called up Friday and went 1-for-13 with a double.
Oakland's bench Thursday consisted of catcher Landon Powell and outfielders Travis Buck and Rajai Davis. Powell, however, tweaked his right hamstring Monday night and is said to be extremely limited.
The bench could get an extra body as early as Friday if infielder Nomar Garciaparra, out with a strained right calf, is activated from the 15-day disabled list. When Garicaparra returns, the A's are expected to go back to a seven-man bullpen.
Mychael Urban is a national writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.