MANKATO, Minn. — Ball hawking has become an annual rallying cry for a Vikings defense that has talked about turnovers a lot more than it has generated them.

Coach Leslie Frazier’s opening speech at training camp last week included another challenge to steal more possessions and protect the football, supplementing his presentation with a data-driven lesson about the impact turnovers have on a team’s bottom line.

“As good as we think we can be, if we’re turning the ball over and not taking the ball away, it doesn’t matter,” Frazier said. “We may put up a lot of yards. We may be stingy in certain areas. But if we’re turning the ball over or if we’re not taking it away, we’re not going to win that many games in the NFL.”

The Vikings finished minus-1 in turnover ratio last season, joining the Indianapolis Colts (minus-12) as the only negative teams to qualify for the playoffs. The Green Bay Packers quickly disposed of the Vikings 24-10 in the wild-card round. One reason: Minnesota finished minus-3 that night at Lambeau Field.

During the regular season, the Vikings won the turnover battle in each of their 10 victories and lost it in all six defeats. And they left plenty of game-changing plays on the field.

Potential interceptions bounced off hands. Tipped balls fell to the turf. Colliding defenders negated interceptions.

Minnesota’s 10 interceptions tied for 27th among the NFL’s 32 teams. Moreover, its 18 picks the past two seasons are the fewest in the NFL — and during that stretch the Vikings went a league-record nine games without an interception.

The team has not ranked in the top 10 in interceptions since 2006 when Dwight Smith, Darren Sharper and Antoine Winfield led a genuine ball-hawking unit that finished fifth with 21.

In camp, defensive backs have played aggressively in full-team drills, attacking the ball as much as receivers. But results have been mixed. Last August, the secondary looked good during drills only to have its production shrink when it mattered during the season.

“We’re going to hustle; we’re going to run to the ball so that when there is a tipped ball, when there is a ball on the ground, we have more purple jerseys around that ball than anyone else,” defensive coordinator Alan Williams said. “So that is a priority in our camp, (and) it will be as we are going into our season and as we practice.”

Defenders have to balance aggressiveness with completing their assignments. But the unit is on notice to do more than just knock down a pass. Swarming to the ball and chopping it out are priorities.

“That’s got to be something we emphasize every day, getting that ball out,” linebacker Chad Greenway said. “We’re definitely conscious of it, and we’re definitely flying around on defense. It’s just a gang mentality that we’re just going to go out there and get two or three (turnovers) a game no matter what’s going to happen.”

Stealing possessions and shortening the field has practical advantages, but Greenway noted the psychological boost turnovers have on teams that create them and the letdown suffered by teams that cough them up.

Frazier points out that in 2012 teams that scored a defensive touchdown won 75 percent of their games.

The Vikings’ defense scored three times last year — on two interceptions returns by Harrison Smith and one by Everson Griffen — and won all three games. Timing was everything.

Griffen’s 29-yard return off St. Louis quarterback Sam Bradford in Week 15 helped turn a 10-point lead into a 36-22 rout for the Vikings. Smith picked off Chicago’s Jay Cutler late in the third quarter and doubled the Vikings’ lead from 14-7 to 21-7 in a 21-14 win.

Against Arizona in October, the Vikings were clinging to a seven-point lead to start the fourth quarter when Smith intercepted John Skelton and scored what turned out to be the winning margin in another 21-14 victory.

Since 2008, the Vikings are minus-15 in turnover ratio, having only finished positive in 2009, when Brett Favre was slinging touchdowns and they were plus-6.

Turnovers positively matter.

Only six of the 47 Super Bowl champions finished the season with a negative turnover ratio, including just one in the past 25 years — the 2007 New York Giants (minus-9).

“We believe we can do a better job of taking the ball away and decreasing our giveaways, and that we have a chance to be that much better as a football team,” Frazier said.

Follow Brian Murphy at twitter.com/murphPPress.

VIKINGS’ GIVE AND TAKE

-15

turnover ratio since 2008 (15 more turnovers than opponents)

10

interceptions in 2012, tied for 27th in NFL

18

interceptions since 2011, fewest in NFL