QB Ben Rothlisberger has literally been running for his life behind their offensive line for several years now. Martin will help keep Big Ben off the ground. He is versatile enough to play either the left or right tackle position.
The Steelers don't have good depth at tackle, but what they really need on the offensive line is guards. I wouldn't rule out someone like Martin, but who knows? Nearly all other mocks right now have the Steelers taking Alabama linebacker Dont'a Hightower, who certainly would make sense from a positional perspective, but it's impossible to tell what the Steelers might actually be thinking.
For more on the Steelers, check out Behind The Steel Curtain.