The former New York Giant rescued the running game, which struggled mightily at the start of 2007. Without him, it's likely the Packers would not have won 13 games.
Knowing that, here's a cause for concern: Hamstring injures have a way of hanging around like Gilbert Brown at an all-you-can-eat restaurant. And a hamstring injury is what Grant has been dealing with since training camp.
He's still not 100 percent, and although he says he will play Sunday at Detroit, the bigger question is whether Grant will be completely healthy this season. Knowing how much he needs a healthy hamstring and knowing there's not a lot of time for rest during a season, Grant might be running with one tire not quite inflated to the recommended pressure.
Coach Mike McCarthy has to determine how to use Grant. Even not at 100 percent, Grant demonstrated last week in just 12 carries he's better than anyone else the Packers have to run the ball.
He gained 92 yards and had a 57-yard scamper in which he said he didn't turn it loose for fear of aggravating the injury.
"He wants to go, but we're also conscious that it's a long year," McCarthy said. "There's a lot of football left in front of us."
As the season progresses, however, the $64,000 question is whether Grant will be able to shoulder the running load this season. If he can, his presence takes pressure off of Aaron Rodgers. If not, the offense will suffer.
Hamstring injuries are not ones to heal in a week or two. Complete rest is usually the recommendation to cure the injury, but Grant can't rest now if he wants to stay on the field. His best resting period is over the bye week. After the Oct. 19 game against the Colts, the Packers don't play until Nov. 2 at Tennessee.
Before then, Grant's status likely won't improve immensely. The more he tests the hamstring, the more likely it is to not heal 100 percent.
He can stretch all he wants and take medical treatment to get through the season. But what if he slips on a slick field? That happens, especially in December in Green Bay.
The Packers paid Grant in the offseason for one reason — they believe he is a feature back in the NFL. Last year, Grant showed he was.
This year, Grant and the Packers were excited to see what No. 25 could do over a 16-game stretch. In the season opener, Grant showed he can be real good, but what if his hamstring was 100 percent?
He said he could've scored on that 57-yard run, if healthy. "If" is never a word you want to use, but in Grant's case, it might be a word used frequently. As in, "if Grant were healthy, how good would the offense have been?"
That's a question the Packers want to put to rest, but at least for the near future, Grant's hamstring will be an issue, especially with Brandon Jackson banged up and rookie Kregg Lumpkin as the No. 3.
If the Packers felt real good about Jackson and Lumpkin, they could rest Grant for a couple weeks and see where that takes them. The Packers aren't doing that because they know an 80 percent Grant is better than what is behind him.
"Do I feel like I have an edge even more when I'm 100 percent? Absolutely," Grant said. "I do feel like I can still manage to perform at a high level."
Maybe so, but as Grant indicated after Monday, he's not 100 percent. The Packers need a game-breaker at running back, and Grant is that when healthy. Will we see Grant healthy in 2008? Kind of like a hamstring injury, we'll have to wait and see.
Doug Ritchay is a frequent contributor to PackerReport.com. He has covered the Packers since 1993. E-mail him at email@example.com.