SANTA CLARA, Calif. — A few young men are making a big impression this week at the San Francisco 49ers' rookie minicamp.

Of course, that's what the team expects after going big last week in the NFL draft.

The 49ers improved their size in practically every area of their offense during the annual college lottery, and offensive coordinator Jimmy Raye already is envisioning how the new parts will fit into an attack that ranked just 27th in the NFL last season.

"When you get 600 pounds of offensive linemen in the first round of the draft, then add another 240 pounds of runner to that, there would be room for optimism," Raye said Saturday.

San Francisco selected Rutgers offensive tackle Anthony Davis with the No. 11 overall selection last week, then grabbed Idaho guard Mike Iupati with the No. 17 pick.

As the first offensive linemen selected among the top 20 picks in the draft by the 49ers since the 1970 NFL/AFL merger, Davis and Iupati come to San Francisco with high expectations to make an impact on a unit that has struggled in recent seasons.

The team put Davis at right tackle and Iupati at left guard this week the positions at which they are expected to compete for starting roles this year once the rest of the veterans join the competition.

Against other rookies, undrafted free agents and tryout players, Davis and Iupati stand out in the trenches simply by their sheer size and talent.

"They've shown the athleticism, the quickness, the explosion, the power, the heavy hands, the ability to drop their weight, sink and anchor," Raye said. "In the drills, they've shown all that."

Actually, Raye was selling the pair a bit light in the size department. Davis carries 323 pounds on his 6-foot-5 frame and the 6-5 Iupati tips the scales at 331 pounds, making him the heaviest player on the San Francisco roster.

That's not by mistake. The 49ers are looking to get bigger and brawnier not just along their offensive line, but throughout their entire roster.

"(Coach Mike) Singletary, he brings in a lot of big guys," Iupati said. "From what I've seen from the veterans here, they're just big guys. I took 10 (pre-draft) visits, and this was the biggest offensive line group I saw."

That meets a clear objective for the 49ers, who envision themselves by design as a power rushing team. San Francisco, however, finished just 25th in the league last year in rushing offense despite featuring a Pro Bowl running back in Frank Gore.

"It makes it a little bit more obvious of what the coaches are doing here," Davis said. "We are going to run the ball. We will run the ball."

The 49ers got more help in that area during the draft by selecting running back Anthony Dixon and tight end Nate Byham in the sixth round.

The 233-pound Dixon led the Southeastern Conference in rushing last season at Mississippi State, and the 264-pound Byham was considered one of the nation's top blocking tight ends at the University of Pittsburgh.

Both also fit in well with the team's new persona. Byham will be used like a third tackle in some situations and Dixon adds size to the backfield in short-yardage and goal-line situations.

Dixon was the featured back during Saturday's drills, often pushing through bodies up the middle before running to daylight.

"If anybody was going to get in my way today, they was going to get ran over," Dixon said. "My main focus was just to run through everything, and I'm running through things from here on out."

That's how the 49ers like it. And, Raye said, there is a lot to like from the team's first peek at rookies who are expected to contribute by the time the season begins in September.

"Just physically looking at them is a good impression," Raye said. "They've done a good job of absorbing the system to this point. We have to make sure that we don't evaluate them in shorts and T-shirts, but these guys can make us a better football team."