Maybe not eifert, but Hopkins, Patterson, hunter. Big physical wideouts could have certainly helped this team
Probably the biggest problem that effects this team now, and in the foreseeable future, is the salary cap. The Steelers have been forced to make moves that are based more on cap numbers than personnel decisions.
I believe that the biggest reason for this is that defenders do not make an impact on this team until their second contract. In today's NFL, especially under the last CBA, the first contract for a player is a gift to the team. It serves as a tryout of sorts. The teams that are in the best positions are those who have many "first contract" players contributing. Looking at the 2013 Pittsburgh Steelers, you have in and around your starting lineup (cap hit in brackets):
Ziggy Hood ($2.99M)
Maurkice Pouncey ($2.5M)
Cam Heyward ($1.8M)
David Decastro ($1.7M)
Jarvis Jones ($1.5M)
Steve McLendon ($1.4M) - a first contract but paid like it
Marcus Gilbert ($800K)
Mike Adams ($800K)
Le'veon Bell ($700K)
Cortez Allen ($600K)
Without going into details, you can see that we are not robbing the bank on these bargains. These players allow you a ton of cap flexibility while they are under their rookie deals.