HOUSTON -- As the Houston Texans' passing game has struggled this season, coach Bill O’Brien has been leaning on Lamar Miller and the running game.

When the Texans signed Miller during the offseason, they were hoping he would take over a running backs group that was injured and inconsistent last season.

So far, Miller has been a solid addition for the Texans, running for 581 yards and a touchdown on 136 carries. He also has 20 catches for 117 yards and another score.

Miller injured his shoulder Monday night against the Denver Broncos and was not able to play as much as usual. He played just 44 percent of the Texans’ offensive snaps; fellow back Alfred Blue played 51 percent.

“I give the guy a lot of credit,” O’Brien said. “He’s a tough guy. He’s a pro football player. He really came back and kept wanting to play, and I think that’s good.”

Miller was a limited participant in Thursday’s practice, but O’Brien said he was encouraged by what Miller could do during the session. The coach said Miller is day-to-day with the injury.

Though the Texans' offense is searching for consistency, the unit has seen some success in the running game. O’Brien credited the offensive line's improved play for the success of Miller and the running game.

The line has been a revolving door this season after rookie center Nick Martin, the Texans' second-round draft pick, went down during training camp with an ankle injury; right tackle Derek Newton (knees) was lost for the season in Monday night’s defeat at Denver. Houston was also without left tackle Duane Brown for the first five weeks of the season while he was rehabbing a quadriceps injury. With Newton out, veteran Chris Clark, who filled in for Brown at the beginning of the season, and Kendall Lamm will play at right tackle.

“I think the line has done a good job,” O’Brien said. “I think that Brock [Osweiler] has done a good job of getting us into the right play at times. I think the tight ends have blocked well.

“I think the backs are running well. Obviously, Lamar [Miller] is running well, and I think Alfred Blue, when he’s had his chances, other than the turnover, I think he’s really running well.”

Even after the Texans gave Osweiler a four-year, $72 million contract during the offseason, O’Brien and offensive coordinator George Godsey stressed that Houston still wants to have a balanced offense. And so far, that has been the case.

“We’re going to run the football,” Godsey said. “So it helps with play-action, takes a load off everybody’s shoulders in the passing game. Certainly we have to be more productive in the passing game. It’s a unit that has to be more precise.”

The Texans could build upon their recent success running the ball when they host the Lions on Sunday. Detroit has the NFL's 18th-ranked rushing defense, allowing an average of 111.4 yards per game. Godsey said the ground game and the Lions’ run defense has been a focus of the Texans’ preparations this week.

“They have some stout, bigger bodies,” Godsey said. “They’ve stopped some pretty good runners, too, running the football, so that’s a challenge from the running-game standpoint.”