It started with a low rumble, on Sept. 8.

It stopped, suddenly, on Sept. 15, only to re-start nearly a month later on Oct. 6.

During a 19-17 win on Sunday in Baltimore, the freight train that is Eddie Lacy was down the tracks at full force.

The Green Bay Packers rookie running back rushed 23 times for 120 yards, averaging 5.2 yards per carry. This comes on the heels of a 99-yard effort against Detroit on Oct. 6, which was Lacy’s first action since suffering a concussion against Washington back in week 2.

As a team, the Packers have now rushed for 641 yards the last four weeks.

"We want to run the ball," left tackle David Bahktiari said. "You add certain things to our arsenal, to our offense. We become a better offense. We already know we can throw the ball. That’s a given when you’ve got number 12 (Aaron Rodgers) back there. Give him time, and he’s going to get his. We’ve got an element like the run game, that just makes us that much more dangerous. There’s multiple dimensions you’ve got to watch for. They want to play Cover 2, have two guys deep all day, we’ll run the ball. It’s simple football, football 101."

James Starks ran for 132 yards against Washington after Lacy’s injury, Johnathan Franklin rushed for 103 against Cincinnati with both Starks and Lacy out.

Now, Lacy seems to have hit his stride.

"He’s the biggest running back we’ve had that I’ve played with," guard T.J. Lang said. "Which, when you think about those guys you tend to think more downhill, power runners, but he’s a guy that’s shown not only can he do that but he can bounce around side-to-side and fit well into what we’re doing zone wise, blocking those zone plays. I don’t really know who to compare him to but he’s definitely a good addition. He’s a good, hard runner.

"He’s got a big skill set. He’s still learning but you’ve got to like the work he’s put in so far."

Admittedly, Lacy was slow in picking up the nuances of the Packers offense. That learning curve is a reason he is still pulled off the field in certain situations, but he is seeing growth.

"Now that I look over it, it was real difficult to just be able to go out there and know you’re running one play but it could change to any play and having to know what those plays are and how it’s going to be checked to," he said. "After going through it for a while and it’s sort of repetitive and you get the hang of certain things and learn certain concepts, it made it a lot easier."

This is important, because with Lacy the Packers’ identity is changing.

Sure, Rodgers is still an MVP-caliber quarterback. And even if there are injuries to the receiving corps, there are options for him to go to, such as tailoring the offense around Jermichael Finley if James Jones and Randall Cobb have to miss any significant amount of time.

But with Lacy running hard, you can see a shift in what could define the 2013 Packers season – a ground and pound type attitude that helps the Packers weather any kind of injury on the outside.