The NFL has evolved in so many positive ways. Tackling isn't one of them.

"Obviously, tackling today is different; very much so," said Vikings linebackers coach Mike Singletary, who made 1,488 tackles during a 12-year Hall of Fame career with the Chicago Bears (1981-92). "When I played, there was more fundamental technique used."

There are many reasons for the fall of the sure tackle and the rise of the missed tackle.

First of all, the NFL isn't a between-the-tackles league anymore, so tackling is harder in an open-field game with offenses spread out to throw more. A year ago, NFL offenses averaged 33.7 passes and 27.2 runs per game.

NFL teams also don't tackle in practice during the season and rarely, if ever, do they tackle in training camp. Heck, teams wear pads only once a week during the regular season under the new collective bargaining agreement.

"We tackled to the ground at Ohio State," said Vikings 13-year veteran cornerback Antoine Winfield, normally one of the best tacklers in the league. "But at this level, people are making way too much money. You don't want to get an Adrian Peterson hurt in a practice."

Singletary said the main reason tackling has declined is a higher priority placed on turnovers in the modern game.

Last year, the top three teams in turnover differential were the Patriots (plus 1.6 per game), Packers (plus 0.8) and Steelers (plus 0.7). The Patriots had the best regular-season record (14-2), the Packers won the Super Bowl and the Steelers played in the Super Bowl.

"When teams began to see what the numbers are when you get turnovers and when you don't, it's pretty staggering," Singletary said. "When players started going for all the strips and trying to create turnovers, the emphasis shifted from having good tackling form to being a turnover team. Personally, I think turnovers are important, but not at the expense of good tackling."

Defenders also go for the big SportsCenter hit at the expense of fundamentals.

"It's guys just not really wrapping up as much as they used to," Peterson said. "They're trying to make a big hit, hoping the guy will fall down. But that's not what happens with a lot of players."

The Vikings missed a number of key tackles in last week's 24-17 season-opening loss at San Diego. They missed two tackles on one simple checkdown to a running back that went for 37 yards and set up a touchdown.

Next up is Buccaneers running back LeGarrette Blount in Sunday's home opener. According to STATS Inc., the 6-foot, 247-pound Blount had a league-high 29 broken tackles in 201 carries last year.

"The technique of tackling is what's really important," Singletary said. "You have to play in a good football position. Bent-kneed for good leverage, play face up, get your head to the side of the football on one side or the other and get your shoulder pads on the guy.

"If you're running full speed and you have your head down, it's not going to be a good situation. See what you hit, I always say. See what you hit. Hit what you see."

Mark Craig • mcraig@startribune.com