SANTA CLARA (AP) — The San Francisco 49ers have improved in just about every facet of the offense this season. But there is one area where they didn't really need to get much better.
The 49ers are protecting the football better than anybody else in the NFL, and their turnover-free play is reaching historic proportions.
San Francisco hasn't committed a turnover in six consecutive regular-season games dating back to last season, the second-longest streak in NFL history. The 49ers can match the league record set by the 2010 New England Patriots on Sunday night when they face the Detroit Lions.
Leading the way is quarterback Alex Smith, who hasn't thrown an interception in a franchise-record 185 consecutive regular-season passes. Smith threw just five picks last season — the fewest in the league for a regular starter — as San Francisco committed a NFL-low 10 turnovers.
The 49ers have not committed a regular-season turnover since Smith's second-quarter interception against the Baltimore Ravens on Thanksgiving night last year.
They have not lost a fumble since tight end Vernon Davis fumbled after catching a pass from Smith in the fourth quarter of a Nov. 6 victory at Washington. The 49ers have a streak of 36 consecutive quarters without losing a fumble.
Smith doesn't downplay the significance of turnover-free play in San Francisco's rise back to NFL prominence.
"In the history of the NFL, the strongest correlation to winning and losing is the turnover ratio," Smith said. "The turnover battle is the No. 1."
The 49ers know all about it. They finished 13-3 last season and made their first trip to the playoffs since 2002 after leading the NFL with a plus-28 turnover differential, one of the league's best since the 1970 AFL-NFL merger.
The previous seven seasons, all of which they finished without a winning record, San Francisco committed 221 turnovers and had a cumulative turnover differential of minus-57.
The 49ers changed that dramatically once Jim Harbaugh and a new coaching staff took over the team last year. San Francisco matched the NFL record for fewest turnovers in a season, also held by the 2010 Patriots.
"Ball security relates to your team being successful, and we're very serious about that," Harbaugh said.
The 49ers make a "commitment to taking care of the ball," Harbaugh said, and Smith was transformed by that approach last season.
In his first six NFL seasons, Smith threw 53 interceptions and lost 16 fumbles while throwing 51 touchdown passes. He threw 17 touchdown passes last season, when Smith set a team record for fewest picks in a season, and he lost just two fumbles.
Smith has been most impressive keeping the ball out of the hands of opposing defenders when he goes to the air. He completed 20 of 26 passes without an interception during last week's 30-22 victory at Green Bay, breaking Hall of Famer Steve Young's previous team record of 184 consecutive passes without a pick.
Including San Francisco's two playoff games last season, Smith has now thrown 253 consecutive passes without an interception.
"That's huge, and it's a credit to Alex," offensive coordinator Greg Roman said. "He's got an innate feel for risk management on the fly. A lot of that goes unseen, but it's all calculated by him. He's done an incredible job."
Smith isn't the only one. Three-time Pro Bowl running back Frank Gore, who had two lost fumbles among his 299 touches last season, enters Sunday's game with a career-best string of 226 touches (220 rushes, six receptions) without a lost fumble.
Gore's backup, Kendall Hunter, has never fumbled in his 17 career games. Gore and Hunter combined for 153 yards rushing on 25 carries last week against the Packers.
Harbaugh credits running backs coach Tom Rathman, who played fullback for the 49ers from 1986-1993, with "doing as good a job as any of us have ever seen done," in preparing his unit to protect the football.
"There's no secret to it. We preach it, but we don't preach it to the point of suffocating people," Roman said. "But everybody understands what we're trying to get done.
"We emphasize ball security, how the defense tries to strip the ball, and do all the different things to educate the players on what's coming at them. Anybody that handles the football understands that they've got the collective fate of the team in their hands. If you have the ball, it's your job to protect it. It's that simple."
The 49ers also are getting some help in that regard from their own aggressive defense, which tied for the NFL lead last year with 38 takeaways.
Coaches have instituted "Takeaway Thursdays" each week in practice, where San Francisco's defense stresses stripping the ball and picking off passes from the team's first-string offense.
"It's something that starts on the practice field, and that's where we get it," Smith said. "It starts there, and then carry it over to the field."