My take on their current losses
Like you said AB702, it's contributing to the absence of Troy Polomalu. When you think of the current Steelers defense, Tro Polomalu is right at the top of the list. His havoc hard hits and nose for making INTs' can frustrate opponents to a T. The last time the Steelers had a defensive INT was back in the first game against the Titans by Troy Polomalu.
Psychologically, the absence of TP43 has effected the Steelers defense that they are not playing up to par like they know they can. A hard nosed defensive unit who can step toe to toe with the best of them. The guys have to find a way to overcome the absence of TP43 and get back to the basic by being the best James Harrison, James Farrior, LaMarr Woodley, William Gay, Ike Taylor, Tyrone Carter, Brett Kiesel, Lawrence Timmons, Ryan Clark, Aaron Smith, and Casey Hampton they have to be. These close losses have to be stop now. Focus on the real sht that made them who they are and f**k that sht about not playin well w/o #43. Get out there and start playin smart defense and execite it like they have a purpose.