Tom Silverstein gathered some quotes from Green Bay Packers offensive coordinator Joe Philbin. This is the money quote, and it's why I suspected they selected Mississippi State LT Derek Sherrod. From JS Online:

Said running game at Miss. St. is different, but you can see him go to the second level and move his feet well.

Watching Sherrod on film, I noticed that he seemed light on his feet, and he often moved down field to block a linebacker or defensive back, which often created a huge opening for a running back. It's hard to tell how that translates to the NFL from the video I watched, but apparently Philbin watched a lot more video than I did, and is confident that Sherrod can bring those same skills to the NFL.

This has been a point of emphasis I've read during different press conferences, that Mike McCarthy wants his offensive lineman to get down field and give the running backs a better chance to make a big run.