SANTA CLARA – The 49ers enter tonight's game against Chicago searching for both a win and an offensive identity.

They spent the offseason molding themselves as a power-running team, but Sunday against Tennessee they ran more than half of their plays with Alex Smith in the shotgun, a decidedly un-smash-mouth formation.

The 49ers lost because they committed four turnovers. Still, coach Mike Singletary called Sunday's game "one of the better offensive performances I have seen since I've been here."

The 49ers threw for a season-high 286 yards, and their yardage total was the team's second-highest this year. The 49ers also scored touchdowns against Houston and Indianapolis on drives in which Smith operated exclusively out of the shotgun.

At the midpoint of the season, the question is whether the 49ers can marry their blue-collar beginnings with a finesse formation.

"I think it's always more difficult to run in the gun," Bears coach Lovie Smith noted this week on a conference call. "When teams need a couple of yards, most of them aren't in the gun. Your fullback in front of a great tailback – I still think that's the best way to run. Or you just let your tailback get the ball deep in the backfield. I don't think that will ever change."

Operating out of the shotgun eliminates the fullback, once a staple of the 49ers' offense. But with fullback Moran Norris leading the way this season, the 49ers' running game has been, at best, inconsistent and, at worst, predictable. Teams merely have added an extra defender along the line of scrimmage and mostly stuffed Frank Gore.

When the 49ers are in the shotgun, Norris is replaced with either an extra tight end or wide receiver. Defenses must account for the pass, which in turn can loosen up the running game. Against Tennessee, Gore took seven handoffs out of the shotgun and gained 40 yards.

"If we can get the safety out of the box and get that extra linebacker out of the box, we can check to a run," center Eric Heitmann said. "I think the best offenses in this league, they'll take advantage of those situations. And that's something we're growing into."

Smith, meanwhile, used the shotgun formation almost exclusively in college, and he has seemed to be at his best when the 49ers are in a hurry-up mode and he is not under center. Asked why he seems more comfortable in the two-minute offense, Smith said he wasn't sure.

"It could be you think that anytime that you are spread out and you're in the gun, all quarterbacks are going to see things better," he said. "I don't know. I'm not sure."

Despite their success in the shotgun, players such as Gore, Heitmann and Smith this week stressed the importance of having a balance between the run and pass and a mix of plays in the shotgun and under center. Versatility, they said, always is a plus.

And having the shotgun is especially handy when the opponent struggles against the pass. The Titans, for example, entered last Sunday's game with the worst pass defense in the league. The Bears, meanwhile, have injuries in the secondary and have allowed two quarterbacks – Cincinnati's Carson Palmer and Arizona's Kurt Warner – to throw five touchdown passes each against them in recent weeks.

"I like the things that work," Singletary said when asked about the shotgun. "I look at, how many yards and how effective is it? How did it fit with our personnel and what we are doing? It is certainly something we have the tools to do. We have Vernon (Davis) here in the tight end spot, and we have three wideouts. We have Gore in the backfield. Those are some great weapons to be able to use."

Read Matthew Barrows' archives and blogs at www.sacbee.com/sf49ers.