SAN FRANCISCO ? Four-and-a-half games after replacing Shaun Hill as the starting quarterback, Alex Smith was asked for his assessment of the 49ers? offense.

?Some good. Some bad. Some in-between,? Smith concluded.

Time is running out on the 49ers? playoff hopes. In a final six-week stretch filled with must-win games, the 49ers (4-6) face the first ?biggest game? of the remainder of their season today against the Jacksonville Jaguars at Candlestick Park.

The 49ers? passing game has been very good in spurts since Smith took over. But his two best halves of football took place with the 49ers trailing by three touchdowns against the Houston Texans and the Green Bay Packers.

Working predominantly from the shotgun formation, Smith has piled up the statistics. His success in working from 5 yards behind center Eric Heitmann has prompted many to surmise the 49ers should line up in that formation all the time.

Generally, the 49ers have used the shotgun formation only on third downs, two-minute drills or when the team was far behind at halftime.

The 49ers rallied from a 23-3 halftime deficit against the Packers last week to close the final margin to 30-24.

?I don?t think the formation per se had a whole lot to do with it,? 49ers offensive coordinator Jimmy Raye said. ?The fact that we were in a semi-rally mode because we were down by four scores (actually, three) had something to do with it.?

Regardless of the reason, the statistics show Smith has experienced more success throwing the ball from the shotgun formation this season.

In 92 pass attempts from the shotgun, Smith has competed 58 throws (63 percent) with seven touchdowns and three interceptions. His passer rating in the shotgun is 95.3. Moreover, he has been sacked just four times.

While attempting 63 passes under center, Smith has completed 37 (58.7 percent) with two touchdowns and four interceptions with a passer rating of 61.3. Even with the fewer attempts, Smith has been sacked nine times.

First-year 49ers quarterbacks coach Mike Johnson discovered this offseason that Smith was still far behind in grasping the fundamentals of the position. Smith, who played exclusively in the shotgun/spread formation under Urban Meyer at Utah, appears more confident in the shotgun formation.

Coincidence or not, Smith threw an interception the only time he lined up under center in the second half of last week?s game.

?Really? I didn?t know that,? Smith said. ?I guess when I look at that, in that one example, I don?t see the correlation there. I understand that?s what the statistics say but that was a unique deal.?

The Jaguars have studied the 49ers? first 10 games, and coach Jack Del Rio said he is not worried about facing a team that goes with a shotgun offense for large periods of today?s game.

?We?re not concerned with how they want to approach it,? Del Rio said. ?We have plenty of tape to evaluate with them doing all sorts of different things offensively. Like most teams, that?s something they have in their ability.?

Running back Frank Gore is still considered the 49ers? main offensive weapon. There is less variety of run plays ? mostly slow-developing draws or counters - a team can utilize from the shotgun formation.

?When you have a running back like Frank Gore, he is a hit-the-hole-downhill guy,? 49ers coach Mike Singletary said. ?He?s not a fidget to the right and then give him the ball. It?s not like you?re under center when (the quarterback) is going back, he?s going forward, and he?s hitting that hole.

?So it?s different for the running back. For the quarterback it?s great. But it?s different for the running back when you?ve got that kind of running back.?

The 49ers have lacked a true identity on offense. They began the season with the hope of being a power-running team that could wear down the opposition. But the offensive line has not delivered.

With the emergence of tight end Vernon Davis and the Week 6 addition of receiver Michael Crabtree, the 49ers have become tilted more toward the passing game.

?I think this offense has been in transition since I?ve been here,? Raye said. ?You name a week that we haven?t been in transition, from an injury standpoint, from a runner standpoint, a receiver standpoint, an offensive line standpoint. It has been a constant flow of transition.?

Raye expressed optimism Smith?s statistics will continue to improve ? regardless of the offensive formation ? as he becomes more comfortable in his surroundings.

?I would anticipate going forward that as we improve in other areas of our play offensively, his growth will continue,? Raye said. ?He?s become a little more assertive. You?ve got to remember that as he and the offense become more compatible and friendly, I think the less anxiety he?ll have as he anticipates and knows the players he?s playing with.?

For more on the 49ers, go to Instant 49ers at blog.pressdemocrat.com/49ers. You can reach Staff Writer Matt Maiocco at matt.maiocco@pressdemocrat.com