As the 49ers opened a three-day mini-camp Tuesday, the focus was on improving what offensive coordinator Greg Roman called “situational football.” That means more work on red-zone plays and third-down conversions — two problem areas that plagued the 49ers even during a season that took them to the brink of the Super Bowl.

Roman acknowledged Tuesday that the 49ers felt limited last season by an off-season lockout that erased the traditional summer team activities. Robbed of the chance to fully install Coach Jim Harbaugh’s offense, “we kind of had to throw it all against the board and see what stuck.”

“I can assure you that it did put us under a tremendous amount of stress,” Roman said.

During this camp, Roman will get chance to improve an offense that finished 26th in the NFL in yardage last season. The 49ers ranked 31st in third-down conversion percentage.

Was that because of a lack of execution? Or was the offense lacking in complexity?

“It’s probably a little bit of both,” Roman said. “I mean, it all comes down to execution and a lot of it is time on task (in practice).

“The more you do something, the more you’re going to get out of it. We’ve got more time so I think we’ll be more efficient and maybe be able to branch out a little more, too.”

Quarterback Alex Smith, too, is eager to see what the 49ers can do now that they have a whole off-season to learn the system. During the lockout of 2011, Smith arranged for players to practice together at informal workouts that became known as Camp Alex.

“It’s kind of laughable to compare this to last year,” Smith said Tuesday. “This time last year we were at San Jose State doing what we could, which wasn’t much.

“This year, even with the limited time and the new regulations, we really got a lot of work in and really pushed the tempo. We’re not even close to where we were last year.”