The Lions 2 headed monster at running back is one of the keys to their success. And when I say 2 headed, they truly are that.
Through 12 games the combination of Gibbs and Montgomery are almost mirror images of each other in so many aspects. With rushing yds being the only outlier. Here's a breakdown.
Rushing:
Gibbs, 163 Att., 973 Yds, 6.0 Avg. 10 TD's
Monty, 166 Att., 720 Yds, 4.3 Avg. 11 TD's
Receiving:
Gibbs, 28 Rec., 282 Yds, 1 TD
Monty, 27 Rec., 277 Yds, 0 TD
To be separated by 2 total touches (3 rushing, 1 Receiving) is amazing, not to mention both have scored 11 TD's each.... in 12 games,

That 6 yds per Att by Gibbs in the run game is what really stands out to me. That guy is explosive and a real Home Run threat when he gets the ball.
I think this combo is what really drives this team, more so than the passing game. You just can't forget about the running game when playing the Lions, and if you can run, as we all know, it opens up the pass, which is why I feel Goff is so successful in Detroit, because he doesn't have to be "The Man" for them to win.