RENTON, Wash. -- While it's again a mystery as to who will take the lead role this week in the Seattle Seahawks' ever-unsettled backfield, Tom Cable made one thing clear. He wants third-year running back Thomas Rawls to play with the patience and discipline that have too often escaped him over his past two seasons.

Or, as Cable put it bluntly ...

"Don't try so damn hard."

That was Cable's response when asked what Rawls needs to do Sunday against San Francisco as he returns to Seattle's backfield a week after he was a healthy scratch for the second time this season.

"You see it all the time when guys are trying to make a statement or they're trying to stake a claim to something, sometimes they kinda overstep on the gas, if you will," Cable continued. "He just needs to relax and be Tommy and play ball."

Cable, who coordinates the Seahawks' running game in addition to coaching their offensive line, has seen Rawls' career sputter after a tremendous start, largely due to injuries. He looked like Seattle's running back of the future as an undrafted rookie in 2015, when he stepped in for an injured Marshawn Lynch and rushed for 830 yards and a league-high 5.6-yard average per carry. But his season ended in mid-December that season when he broke his ankle.

Rawls missed the final three games of 2015 plus the playoffs and then missed seven regular-season games in 2016 with a cracked fibula. He was in line to be Seattle's starter entering this season but a high-ankle sprain in August opened the door for rookie Chris Carson, who held the job before landing on injured reserve.

Rawls showed some glimpses of his 2015 form last season, when he set a Seahawks postseason record with 161 yards in a wild-card win over Detroit. He also ran for 106 yards on only 15 carries in a win over Carolina in December. But even with that performance, Rawls has only averaged 3 yards per carry in 16 regular-season games over the past two seasons.

Rawls is not a patient person by nature. He talks a mile a minute and he tends to play that way, sometimes to his detriment. Cable, though, thinks some of that over-eagerness is rooted in a desire to prove that he's worthy of being Seattle's starter, pressure he may not have put on himself when he was only filling in back in 2015. Lynch missed nine games that season then went into a one-year retirement.

"Put yourself in his shoes," Cable said of Rawls. "Couple years ago, he's as hot as it gets. He's playing and he's marching towards a thousand yards and he has a horrible [ankle] fracture. I think ever since then, coming back, and the departure of Marshawn, watching it I've always felt like he's thought that, 'Hey, I have to be the guy now, I have to take over.'

"I think unfortunately for him and us, he's just trying too darn hard. When you watch him run two years ago, he's kind of a consistent, calm, explosive guy and not trying to force anything. Still trying to get him back there."

When asked about how that over-trying manifests itself on the field, Cable mentioned decision-making. He said Rawls doesn't always exercise the discipline that it takes to read a play properly in the backfield and react accordingly. He'll constantly remind Rawls, 'You get one cut. You don't get three, you get one. Make one cut. One cut."

"Just trying to get him to take a breath, stay in the moment, don't try to do too much," Cable said. "You're not going to become a 1,000-yard runner on one run. You're not."

One play that illustrates Rawls' impatience came in Week 7 against the Giants. He caught a screen pass and had room to run, but he cut back to the inside and barreled over a defensive back. The physicality was great. It's what Pete Carroll covets in running backs and what made Rawls something of a personal favorite of the coach when he watched Rawls' college tape leading up to the 2015 draft.

But Rawls may have left some yards on the table on that play.

"One of the things we know about Thomas is that he’s ‘Thomas the Train’ for a reason. He's looking to hit someone," offensive coordinator Darrell Bevell said. "That one screen against the Giants you’re talking about, there were linemen there. We needed just a little bit of patience, let those guys get out in front of you, and he was probably going to get better yardage. I think he was dead-set on hitting somebody at that point, and he did. It’s a good play, but I think there was more there.”

Cable said over-trying has been an issue with Seattle's other running backs and even some offensive linemen this season as all involved have tried to get a sputtering running game going. The Seahawks rank 18th at just over 104 yards per game, and that's with quarterback Russell Wilson's 541 rushing yards leading the team.

It hasn't helped that Seattle has had a revolving door at tailback. Carson was the primary option before he went down in the fourth game. Rawls and Eddie Lacy split carries for the next three games before Seattle decided to give Lacy a shot to take over, but he promptly got hurt. Practice-squad call-up Mike Davis got his turn to start Monday night, but a groin injury ended his impressive Seahawks debut and will likely sideline him this week.

Rawls was a healthy scratch Monday night, but with Davis banged up, he'll be back in the mix against San Francisco along with Lacy and J.D. McKissic.

"We're going to give them all a chance," Cable said. "We know who we've got available this week based on Mike's injury. It's really about the discipline of it and believing in the spot and believing in what you're doing and don't press, really."