Midway through training camp, RB Cedric Benson was without a team and wondering why no one was calling. Now, with the season opener against the 49ers just three days away, he’s atop the depth chart of one of the best teams in the league.

The streets-to-starter plotline is a nice one, but it doesn’t do the whole story justice. It’s important to remember that Benson’s signing probably wouldn’t have happened if not for the turf toe injury James Starks sustained in the first preseason game at San Diego. Benson was signed a few days later.

It’s important, too, to recall that many people initially thought the fit made no sense – Benson was a high-volume runner who needed lots of touches to get going, and the Packers were a pass-first, pass-often offense. He also had never been in a system like Green Bay’s. There were calls from fans and conjecture from media as to why the team didn’t go after their beloved veteran RB Ryan Grant, who’d spent seven seasons in Green Bay and was available.

Then came the questions about Benson’s age (29) and the vehicular references to the tread on his tires, all the miles on his legs and how much gas he had left in the tank after more than 1,500 career carries. Benson responded to those doubts definitively, with a striking rushing display in his Week 3 debut against the Bengals, the team that had cut him loose. He ran six times for 38 yards, including impressive gains of 8, 8, 9 and 11 yards, and caught a 10-yard pass. Cue the acclaim.

And then, in the preseason finale, coming off that strong performance against Cincinnati, Benson fumbled on his first carry. All of a sudden, everyone remembered the Hyde to Benson’s Jekyl was ball security. He led the NFL with 12 fumbles over the previous two seasons.

He’s the proven runner the Packers need to balance their offense and keep opposing defenses honest. But fumbling is a cardinal sin for Packers running backs, and his propensity to do so could ultimately see him forfeit that starting spot to second-year RB Alex Green.

“You’ve got hold it high and tight going through the holes,” Benson said. “You have to train yourself to be explosive in your cuts while still keeping the ball tight to your body. You have to train yourself to control the football.”

The Packers are certainly taking it upon themselves to train him, too.

“There’s three or four drills we do dedicated to ball security that I didn’t do in other places,” Benson said.

Benson has been crash-course cramming trying to learn the Packers offense the past few weeks. He sits in on quarterback meetings, buries his nose in the playbook and peppers teammates with questions. Coach Mike McCarthy said Thursday that the effort is noticeable and the knowledge is emerging.

“I feel very comfortable that he knows the game plan,” McCarthy said. “It’s not the football understanding that’s an issue, it’s just once in a while a term comes up – our language is not a constant language, our playbook isn’t a book that you just change the date on. The language is ever evolving and things change. This was called something last week, it’s called something different this week. That’s just kind of part the way we operate right now.”

Follow Packers reporter James Carlton on Twitter @CBSSportsNFLGB.