Generally in a gap blocking scheme, that's kind of what you want out of your RB. Get to the whole and hit it hard, with minimal dancing and cutbacks.
I may be a little biased, but I try to stay as objective as possible with Greene. He certainly isn't much of a threat to make people miss, but he's also a threat to turn a one yard run into a 3 yard run, which McKnight and Powell aren't. The OL has done well at times tonight creating nice holes, but they've also had some difficulty blocking in the run game, both physically blocking and with an assignment or too.