Niners head coach Jim Harbaugh indicated Sunday that injured wide receiver Michael Crabtree could return to practice as early as this week.

The bad news? It won't matter who occupies San Francisco's skill positions if its offensive line doesn't dramatically improve.

In a 30-7 loss to the Texans on Saturday, the 49ers' front five was dominated, marking the second time in three preseason games that the unit was comically outclassed.

San Francisco allowed three sacks, and quarterback Alex Smith, who was hit five times, endured a pounding despite dropping back to pass only eight times.

In a 24-3 loss to New Or- leans in its opener, the 49ers had been blindsided by the Saints' blitz-happy attack - unusual for the preseason - en route to allowing six sacks. On Saturday, Houston played a mostly vanilla, pressure-free scheme, but San Francisco's linemen were routinely beaten in one-on-one matchups.

"What the defense was presenting us should not have been complex for us, and yet we were violated at times," Harbaugh said. "When that's happening, you have to look at all three phases of what you're doing. What you're doing schematically, how you're doing it and who's doing it. And those are really the only three things you have to focus on. And that's what we'll do."

Harbaugh's concern regarding his offense was hard to miss - "I'm not as discouraged with the defense," he said - after the Niners managed zero points, six first downs, 105 yards and ran only four of 38 offensive plays in Houston territory.

The unit appears as if it could be getting a potential lift with the return of Crabtree, who has been on the physically unable to perform list since the start of training camp. Harbaugh said it is "possible" when asked if Crabtree might return to practice this week.

Crabtree has been sidelined with an undisclosed injury to his left foot that he sustained during the 49ers' players-only minicamp in early June at San Jose State. The Sacramento Bee reported Sunday that Crabtree's foot was broken and that it required surgery before training camp. Crabtree had a stress fracture in the same foot that also required surgery shortly before San Francisco drafted him in 2009.

Marcio Jose Sanchez/AP

Crabtree, who has not played in an exhibition game in his three seasons, won't play in the preseason finale Thursday in San Diego. Harbaugh hopes a much-improved offensive line appears against the Chargers.

"We have to do better in our pass protection," Harbaugh said. "I think that was obvious to anybody. And some of it is coming from technique. Some of it is fundamental. Some we got beat to the punch."

Briefly: Harbaugh said it is likely the 49ers will make their initial cuts Tuesday, but that they could come sooner. NFL teams must trim their rosters from 90 to 80 players by Tuesday. The Niners currently have an 87-player roster. ... Harbaugh praised the play of defensive end Demarcus Dobbs, an undrafted rookie who has two sacks and another tackle for a loss. "He's using his long arms. He's been athletic. He's been physical. ... Very much arrow up on Demarcus Dobbs."