Bolstering both the offensive and defensive lines has been important to Cardinals GM Steve Keim.

The easiest path to NFL success is to put a superstar under center and build around him, but precious few general managers have the luxury of an Aaron Rodgers or Andrew Luck.

The rest must use a variety of methods, and as Cardinals GM Steve Keim puts the finishing touches on his third offseason, the direction he's headed has become clear.

The Cardinals, according to salary cap website Spotrac.com, are the only NFL club in the top-7 in positional spending on both lines. They are fifth in the league with $27.6 million invested in the offensive line and seventh with $26.4 million invested in the defensive line.

Keim won't hesitate to address other positions – the quest to upgrade the roster is never-ending -- but the former college

offensive lineman wants to keep his roots near the line of scrimmage.

"Going back to individual philosophy, for me, you win and you lose the games in the trenches," Keim said. "Part of it could be, too, for the amount of time I've spent here with this organization (since 1999 as a scout), I feel like we've, to some degree, neglected the offensive line. When you look at the big picture and you think about the value of the offensive linemen, it's not only to create balance and to create movement at the point in the run game, but to be able to protect your assets where you have your money – your quarterbacks, running backs who have had some injuries.

"You have to put an emphasis up front, both on the offensive and defensive sides of the ball. To me, to be able to take what was once a glaring weakness and to potentially make it a strength is what can pay huge dividends for us in the future."

The Cardinals have been stingy against the run over the past two seasons, but the loss of nose tackle Dan Williams to free agency and defensive tackle Darnell Dockett in a cost-cutting measure threatened their depth this offseason. Keim responded by adding defensive end Cory Redding and defensive tackle Corey Peters in free agency, and then drafted defensive end Rodney Gunter in the fourth round.

That trio should join some combination of Calais Campbell, Frostee Rucker, Ed Stinson, Josh Mauro, Matt Shaughnessy and

Alameda Ta'amu as the core of a rotation which, ideally, will allow each player to give maximum effort on every snap without the line suffering a dropoff during substitutions.

"(Keim) is a smart man," Campbell said. "I think he did a great job this offseason, bringing in some guys that are our kind of players. I call them dogs. In OTAs you can see the potential of so many of these new guys. I want to see how it's going to be when we put pads on in training camp."

By nature there is not as much rotation on the offensive line, and Keim is aiming for continuity centered around a high-ceiling core. Left tackle Jared Veldheer and left guard Mike Iupati were given lucrative free agent deals the past two years for a combined $75 million, and the Pro Bowl-quality linemen are inked through 2018 and 2019, respectively.

Former No. 7 overall pick Jonathan Cooper has moved to right guard, with the possibility of this year's first-round selection, D.J. Humphries, joining him at right tackle if he can beat out incumbent Bobby Massie. None are older than 28.

The Cardinals improved in pass protection last season, but the running game averaged a league-worst 3.3 yards per carry, which helped facilitate the changes. The Seahawks are seen by some as the barometer among NFC West lines after leading the NFL in rushing (172.6 yards per game) and finishing third against the run (81.5 yards per game allowed) in 2014, but Veldheer disagrees.

"I wouldn't throw around those words so much with Seattle 'dominating' both sides of the line," Veldheer said. "I think they're both solid lines, but I'd take our guys any day over those guys. That's part of the fun part, too, getting that rivalry going, wanting to puff your chest out more than the guy across the line from you."

Veldheer is willing to talk the talk, and after another offseason of upgrades, the Cardinals believe they will walk the walk.

There's a simple pleasure in consistently winning battles against an opponent lined up inches from your face before each snap, and the Cardinals on both sides of the line hope to make it a habit in 2015.

"Man, it's like you're taking the will out of somebody," Humphries said. "You can see it in their face. You can see it in their eyes when they give up. From looking in your eyes, breathing all hard and grunting to looking at the grass, looking around at their teammates. That's when you know you've beaten somebody. I'm ready to get back to those looks."