When defensive end Justin Smith stripped the ball from Eagles receiver Jeremy Maclin in the fourth quarter Sunday, it allowed teammate Dashon Goldson to recover the ball and preserve a 24-23 victory.
It also was indicative of how the 3-1 49ers are winning games this season.
After four games, San Francisco is tied with Detroit for the NFL lead in turnover margin at plus-8.
The number reflects aggression and good fortune on defense, along with an emphasis on avoiding mistakes on offense. This season, the 49ers defense has taken the ball away 11 times (six interceptions, five recovered fumbles) while giving the ball away just three times (one interception, two lost fumbles).
Quarterback Alex Smith, long plagued by turnovers, has been much more careful with the ball this season in running coach Jim Harbaugh’s West Coast offense.
In the NFL, plus-turnover margins generally equate to winning. The Lions are 4-0. Baltimore and Buffalo, at plus-7, are each 3-1, and 4-0 Green Bay is at plus-6.
One statistical expert has written that turnover margin is among the most crucial statistics in football, pro or college. When Dana Holgorsen took over the West Virginia program this year, he told ESPN: “This is not earth-shattering news, but the most important stat in football is turnover ratio. That’s the absolute No. 1.”
After Smith made his big play Sunday, he said going for the ball was on his mind as he chased down Maclin from behind. He said he was “going for the strip or nothing.”
He said pre-game preparation had included discussion about how some Eagles players don’t protect the ball well.
“We spend a lot of time in film room and they go over all of that stuff every week,” Smith told the San Francisco Chronicle’s Eric Branch. “It entered my mind a little bit (as I was running) from behind.”
Goldson says going after the ball is part of the 49ers defensive approach this season.
“We harp on that every week,” he told the Chronicle. “A coach comes in and brings in a highlight reel and shows us how the guys are loose with the football.”
Of course, turnover margin isn’t infallible. Since 2003, San Francisco has finished a season in plus numbers just twice, at plus-9 in 2009 when it finished 8-8 and plus-12 in 2003 when it was 7-9. But from 2004 through 2010 the Niners were a combined minus-57 in turnover ratio.
So far, the turnaround in turnovers is contributing to the turnaround in the standings.
Said Goldson, earlier this year: “You always like to think you can go into a ballgame and get turnovers.”