Ed Bouchette of the Pittsburgh Post-Gazette is reporting that the Steelers did not sign free agent WR Steve Breaston on Friday after he worked out for them on Thursday. However they do not rule out taking a look later if he remains available.
Source: #Steelers won't sign Breaston now. They may revisit him later if he remains unsigned.
— Ed Bouchette (@EdBouchette) March 1, 2013
After working out and taking a physical on Thursday, it is fair to speculate whether Breaston might of failed his physical and they are giving him time to get in shape. Another reason might be that Breaston wanted more money than the Steelers were willing to give.