Which 2012 injuries hurt the team the most?

IMHO, it would be the O-line. The rumors have Starks, Colone, Foster not in the Steelers plans for 2013, so wouldn't that be a step back letting all those guys go and depending on Adams, Beachum, and Gilbert to fill the void?
Even if that works out who plays if they get injured? John Melecki is the only signed O-lineman on the roster then Legursky still has to be signed.

If they do release those three above, we are going to need replacements in the draft no doubt but which rounds?

Considering the above scenario would you take Warmack if he's there when we pick?

I believe it's the OL as well, I can't recall seeing so many injuries to specific group of players. The CBs, RBs, OLmen, and so on...it's normally a player here and there from each unit, but not specifically 1 unit at a time.

Most think the team wont draft an OL or Rb high but I think the opposite for dept and maybe a stater if a Womack falls.

I still say best player available other than obvious lack of need, which is probably only limited to a QB and OC in early rounds. BPA of OT, OG, RB, WR, LB, CB, S. That's a huge realm to choose from. Better get it right.

The most significant injury in 2012 was Mendenhall. Given that Haley's offense was designed for a more effective running game, going into the season without the #1 RB can never be good. The overall poor return from the RB's shows that the team never recovered.

Has to be Ben. Night and day difference on offense before/after his injury.

Yes. Exactly. It has to be BB. We were making due with the OL and a RB by committee. (although I wish they had 1 main RB)

Ben was, at the time, in consideration for MVP- as some of the announcers were talking about his 3rd down conversion rate, etc. We were also controlling the clock big-time, right up until he got hurt. After he went down, it just wasn't the same since...

Biggest injury was BB. Easy. It's not even close.