EDEN PRAIRIE, Minn. -- Minnesota Vikings special teams coordinator Mike Priefer worked two years as the Denver Broncos' special teams coordinator before he took the same job on Leslie Frazier's staff with the Vikings in 2011. On Sunday, Priefer will make his return to Denver in charge of a unit that might be one of the keys to the Vikings winning.

According to ESPN's Football Power Index, the Vikings have the most efficient special teams unit in the NFL through three weeks, having added a total of 16.63 expected points. The Vikings' opponents have the worst starting field position in the league after a punt, starting an average drive at their own 13-yard line, and that's helped the Vikings pin opponents an average of 78.8 yards from the goal line on all drives. The Vikings, on the other hand, have the league's second-best average field position, just 65.2 yards from the goal line.

Special teams isn't the only cause of that discrepancy -- coach Mike Zimmer brought up the San Diego Chargers' 34-yard pass interference penalty that helped the Vikings escape the deep reaches of their own territory on Sunday -- but Priefer's group has been a major source of the advantage the Vikings have enjoyed.

"There's a lot of hidden yardage in the punt return, the punt going down in there," Zimmer said. "Even when we got the penalty on (Chad Greenway's) touchdown, and we kicked it all the way back from (our) 20, we kicked it all the way to the goal line, and they didn't get out past the 20. Those are all ways of trying to create field position."

Punter Jeff Locke certainly deserves some credit after two inconsistent seasons; he's bumped his net average up to 40.64 yards per punt, and has helped the Vikings pin opponents inside their 10 on 27.3 percent of his punts, which ties for the third-highest figure in the league. The Vikings' coverage units have played well too, but Locke is starting to give the Vikings the kind of field position advantage they thought they'd create when they drafted him in the fifth round in 2013.

Locke's net average is still only 15th in the league, but as Priefer pointed out, he's been frequently asked to punt from opposing territory, where the Vikings want him to be more precise than powerful.

"(His average) won’t rank really high right now because we’ve had a lot of plus-50 punts (in opposing territory)," Priefer said. "He’s had six punts downed inside the 20 or fair caught inside the 20. Out of 11 punts, that’s obviously more than 50 percent. That’s my math skills at work, guys -- Naval Academy education.

"So when you don’t have a lot of punts that are backed up, you’re not going to have as many opportunities to have as many high net punts obviously. The other day, he had like a 28-yard net punt. It was a great punt, it was fair caught at the 11. He’s doing what we’re asking him to do and that’s the big thing."

The effect reaches far beyond special teams. It's a major reason why the Vikings have only given up points on 30 percent of their drives -- tied for the seventh-lowest percentage in the league -- and it's allowed the Vikings to score three of their five offensive touchdowns on drives shorter than 60 yards. That kind of an advantage could help sustain the Vikings in Denver.

"A term that you guys have heard me say many times is complementary football and it’s a combination of the offense, defense and special teams working together to help our football team field position," Priefer said. "The last two games especially have been really good complementary football games. I know that’s what Coach Zimmer asks of us on special teams. So far guys are doing a good job."