Gerald Hodges played only 21 percent of the defensive snaps in what might have appeared to be a small role in the Vikings nickel defense during Sunday's 34-6 season-opening victory at St. Louis.

However, when the linebacker's 14 snaps were described to Mike Zimmer as "not a huge role," the Vikings coach reacted like chess champion who treasures every board piece, right down to his last pawn.

"It actually is a huge role," Zimmer said. "Our nickel players tend to get upwards of 600 plays a year."

Hodges didn't play every nickel snap. He's part of a sub package within the sub package and, for purposes here, a good example of how Zimmer gets good mileage out of his depth, particularly on defense.

In 14 snaps, Hodges had four solo tackles. Of those tackles, three came short of the first-down marker on third down. And, yeah, that's kind of a big deal for a defense that just one season ago ranked 30th in the NFL in allowing 44.2 percent of third downs to become first downs.

In last year's season-opening loss at Detroit, the Vikings defense faced a third-and-7 situation in the third quarter. Sitting in the two-deep zone that was the foundation of their defense, the Vikings were beaten for a 77-yard touchdown when Reggie Bush caught a screen pass and split the safeties.

This year, it took four plays for the Vikings defense to face its first third-down situation. On third-and-8 from the St. Louis 42, here's how Zimmer lined 'em up:

• Ten men were within a yard of the line of scrimmage. Eight were in the box, two corners were out wide and the single high safety was Robert Blanton, who was 12 yards deep.

• Among the front six nickel defenders, Everson Griffen was the only starter lined up in his normal spot, right end. Left end Brian Robison was at right tackle, backup tackle Tom Johnson was at left tackle and outside linebacker Anthony Barr was at left end. Free safety Harrison Smith was a shade off Barr's outside shoulder and showing blitz.

• In between Robison and Johnson were linebacker Chad Greenway and Hodges in the two "A'' gaps, which are between the center and guards. Get used to the crowded ''A'' gap look because it's one that Zimmer loves and can use often because of the many variations once the ball is snapped.

"To me, that look is just aggressiveness," Greenway said. "But you don't always have to be aggressive in what you do out of it. It just shows that you're bringing the fight to them."

Here's what happened once the ball was snapped:

• Five defenders rushed: Smith, Barr, Johnson, Robison and Greenway, who was in the right ''A'' gap.

• Two defenders who showed blitz or one would expect to rush dropped into zone coverage: Griffen and Hodges, who was in the left ''A'' gap.

"There are a lot of really good things about Gerald … [and] he seems to be keeping his nose to the grindstone," Zimmer said. "We have to keep our thumb on him just to make sure that he's always being precise in everything. I think because he has so much natural ability, sometimes he'll rely on his athletic ability instead."

Zimmer also said Hodges has good "blitzability." But on this particular play, Hodges dropped and made a nice open-field tackle when quarterback Shaun Hill had to throw a check-down pass to avoid being sacked by Greenway and Smith. Greenway beat the running back while the Rams' poor right tackle was left trying to block Barr and Smith when the tight end released into his pass route.

Monday, Robison was asked how defenders can remember where they are supposed to line up, especially the, um, older gentlemen who spent years lining up in the same spot.

"That's why we practice so much," Robison said. "But even then, this defense definitely makes you get in your playbook. And you can't be afraid to raise your hand when you don't understand something and say, 'Hey, I'm not quite getting what you're saying.' "

Through one week, it's working. The Vikings are tied for eighth in third-down defense (29 percent). The Rams converted only four third downs. Only one of them was longer than three yards (third-and-12).

"You get to play all over the place," said safety Harrison Smith, who had a sack and an 81-yard interception return for a touchdown on third down. "It's a lot of fun as a football player."

Mark Craig • mcraig@startribune.com