So far, it’s been an interesting and productive offseason for the San Francisco 49ers – with still far more work to do.

The San Francisco 49ers remain busy in the free-agent market, in fact, even as they prepare for the start of the NFL Draft on April 26.

Recently, the Niners have interviewed a couple of veteran free-agent guards, Deuce Lutui of the Arizona Cardinals and veteran journeyman Leonard Davis, and now plan to meet with former Ram Jason Brown, who plays both center and guard, according to Eric Branch of the San Francisco Chronicle, citing a report on Sirius/XM Radio.

The three candidates would provide some competition for second-year lineman Daniel Kilgore to fill the only vacancy in the starting lineups for the offense and defense, created when right guard Adam Snyder signed with Arizona.

The fact only one starting job remains to be filled is a testament to the job General Manager Trent Baalke and his staff have done since the end of last season.

The 49ers, in fact, were given an “A” grade for their work in free agency in a recent evaluation of all NFL teams done by ESPN.

Matt Williamson, who covers the NFC West for ESPN.com, noted the 49ers locked up key free agents in their secondary – cornerback Carlos Rogers and safety Dashon Goldson -- and “are returning the league’s best defense intact, even though they had a few prominent players’ contracts expire.”

The team also re-signed starting quarterback Alex Smith after pursuing free-agent Peyton Manning, so Smith – coming off his best season in the NFL – returns continuity. Meanwhile, the team added wide receivers Randy Moss and Mario Manningham and re-signed receiver/kick returner Ted Ginn Jr.

“The new perimeter speed should open up room for the rest of San Francisco’s offense while allowing (coach) Jim Harbaugh to utilize more multiple-receiver sets,” Williamson wrote.

All in all, the team has done exactly what Baalke said he wanted to do, back in February: add in key areas while keeping important pieces from a team that came within one victory of going to the Super Bowl.

“We want to keep our guys in place,” Baalke told Samuel Lam of Examiner.com in February. “The locker room is very important.”