We're going to lean on you for leadership, they told Jackson this past offseason. We're going to need you to play through pain and provide a positive example for younger players.
A few months later, Jackson is still delivering on that expectation.
"There have been times when I wanted to take a day off," Jackson said recently. "But I also knew that wouldn't help us build what we're trying to create here."
This has been another tough season for Jackson and his teammates, as the Rams are 1-13. But it also has been something else: a chance for people to see another side of a player who should be heading to his second Pro Bowl.
For the first five years of his career, Jackson was defined by an enigmatic, high-maintenance personality. Now he has given people more reason to believe in both his substance and his style, especially given that he has carried an entire offense all season.
The most impressive aspect of Jackson's season isn't that he ranks second in the NFL with 1,353 rushing yards entering Week 16 play against the host Arizona Cardinals. What's most impressive is that he has continued to stay productive despite the lack of dangerous weapons around him.
"His determination and his work ethic have been unbelievable," Spagnuolo said.
"He knows there are 11 guys aiming for him on every play because we haven't softened up the defense with the pass. But he keeps finding ways to grind out tough yards."
"Although I have been banged up lately, I was playing at a high level for the first 10 games," said Jackson, who also leads the Rams with 51 receptions.
"It wasn't just about hitting the weight room and letting my God-given ability take over, either. I feel like I've seen every scheme a defense can throw at me and I'm relying on what I'm seeing [on film] to make things happen."
The true testament to Jackson's ability is his consistency.
Only Tennessee Titans halfback Chris Johnson -- the league's leading rusher -- has more 100-yard games this season (nine to Jackson's seven), and 6-foot-2, 236-pound Jackson also has punished defenses with his penchant for gaining yards after contact.
Part of that success has plenty to do with the performance of an improved offensive line. The other part is Jackson's staying healthy -- he missed eight games over the previous two seasons with injuries -- and doing whatever it takes to help the Rams become winners again.
Of that trio, 26-year-old Jackson is the only one with a serious chance of still being around if Devaney and Spagnuolo succeed in this rebuilding effort. So Jackson has to be the man who reminds teammates of what it can be like on a competitive team.
As he said, "Now, no matter what the situation is, we have to keep thinking we can be an explosive offense. I'm always trying to let the guys know that."
I've learned how to go to the coaches in private [to talk about issues]. And that has helped me gain more respect. I've gone from being a look-at-me guy to being one who is a true professional.
”-- Rams RB Steven Jackson
Just as importantly, Jackson has learned how to handle his own frustrations. He openly admits that he has become a more appreciated player in St. Louis this season because he has been less controversial.
In the past, he would vent to the media about his discontent with his role and with the losing. Although Jackson acknowledges that he chafed under the scrutiny of replacing a living legend in former Rams running back Marshall Faulk, the fact is that nobody cared about the reasons. He too often left the impression that he cared only about himself.
This year, Jackson has seen the value of operating differently.
"I've learned how to go to the coaches in private [to talk about issues]," Jackson said. "And that has helped me gain more respect. I've gone from being a look-at-me guy to being one who is a true professional."
Still, Jackson has to be a little concerned about the question of how quickly the Rams can change their fortunes. As good as he's been, the reality is that backs like him generally don't stay productive well into their late 20s.
The league already has seen four Pro Bowl runners in the past couple of years decline rapidly around that age range -- Shaun Alexander, Edgerrin James, Larry Johnson and LaDainian Tomlinson -- and it's hard to think Jackson won't face a similar fate. Right now, he's responsible for nearly 41 percent of the Rams' total offensive yardage.
That's why Devaney and Spagnuolo realize they have to provide him with more support.
"We have to get more playmakers around him," Devaney said. "If the receivers aren't here to do that, then we have to find some. If the tight ends aren't here, then we need to get somebody. If it's the quarterback, then we have to get one. For both the player and the team, we need to get him some help."
Until that happens, Jackson plans to keep up the promise he made in the offseason. He has played through a lingering lower-back injury.
He missed two days of practice with the H1N1 virus last week but recovered in time to gain 82 yards on 20 carries in a 16-13 loss to Houston. Given how much he's been doing for the Rams, he might be battling a few more ailments in the final two weeks.
What Jackson won't do is start believing that his personal success -- he has 6,644 career rushing yards and another 2,287 receiving yards -- can ease the pain of another lousy season.
"I want to be great one day," he said. "I want to have a Hall of Fame career. And right now, I don't feel like I'm creating that kind of legacy."
Even though Jackson is correct, he is doing something that is just as important: He's showing a young, losing team what it takes to be a winner in the long run.
Jeffri Chadiha covers the NFL for ESPN.com.