The only thing difference right now between 2009 and now when it comes to the run game is the OL play. I will hold off judgement on the OL until all five starters are playing and they have played another game or two in the preseason. Friday was not a good start for the run game, but 2 series isn't much of a sample either. It's also worth noting that the Bengals were a top ten rush D last season.
Before people kill me about Thomas Jones being the big difference, what really is different about him and Greene? They both are grinders that average ypc is in the low to mid 4 range, and neither breaks big runs.