Ross D. Franklin/Associated Press

Steve Keim has done a lot since he became the general manager of the Arizona Cardinals 30 months ago.

Keim has watched over a team that won 21 of a possible 32 regular-season games over that time while returning the franchise to the playoffs for the first time in four years. His success made him the Executive of the Year for last season, while he also penned a new long-term deal in February.

Despite all of his success to this point, Keim's most significant moves appear set to come to fruition in 2015.

When he took over the job in January 2013, the Cardinals roster had two glaring holes, no quarterback to rely on and an offensive line that wasn't worthy of playing in the CFL, not least the NFL. Carson Palmer offered a cheap solution to the quarterback problem, but the offensive line would take more time to fix.

The 2012 Cardinals relied on players such as Bobby Massie, Daryn Colledge, Adam Snyder, Lyle Sendlein and D'Anthony Batiste. Levi Brown, the team's starting left tackle, missed the whole season through injury.

Not a single one of the players that Keim was inheriting could be pencilled in as a viable starter moving forward. As such, Keim needed to invest heavily in multiple pieces to build a brand-new line that was worthy of carrying the offense.

It took a few years, but the Cardinals have gradually built one of the more talented offensive lines in the NFL by adding four key pieces.

Jared Veldheer

Jared Veldheer is a 28-year-old left tackle who was signed in free agency last season. He had previously started 48 games for the Oakland Raiders after being the 69th overall selection of the 2010 draft.

Although coming off an injury after the 2013 season, Veldheer offered the Cardinals an established starter at what is typically considered the most difficult position to fill on the offensive line. With great size, athleticism and good technique, Veldheer is both a consistent pass protector and run-blocker.

For any left tackle, it's more important to be an effective pass protector than run-blocker. In Bruce Arians' offense, Veldheer is no exception.

Arians offense regularly relies on deep drops and hard play fakes that stress the blindside protection. While the system also gives help to its left tackle on a regular basis, it definitely isn't an easy situation for Veldheer to excel in. His foot speed and balance in space are routinely stressed.

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Against bigger edge-rushers and when he is asked to work inside rather than step outside, Veldheer can excel by relying on his bulk and long, strong arms. When asked to work outside against faster linebackers and defensive ends, he has just enough foot speed to be an effective pass protector.

This play against the Kansas City Chiefs pits Veldheer against one of the faster edge-rushers in the NFL, Tamba Hali. However, this play also highlights how the Cardinals help Veldheer to succeed.

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Not only did the Cardinals line up a tight end alongside Veldheer, that tight end ran his route across the face of Hali. By doing that, he created hesitation in the defender, as Hali had to brace himself for a potential hit/block attempt from the tight end.

Once the tight end crossed his face, Hali's eyes had to focus in the backfield, where the offense was running a play fake. This created more hesitation, giving Veldheer an opportunity to advance toward him and engage him before he can advance downfield.

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Veldheer is able to control Hali with his hands extended away from his body. As Hali has to fight through the contact, Veldheer is able to knock him backward, further away from his quarterback. Veldheer showed off impressive footwork to set and reset with Hali as he attempted to move downfield.

Hali eventually pushes his way around the left tackle, but he is too far away from the quarterback, and too much time has passed for him to be a factor in the play.

Veldheer wasn't signed to a huge contract as a free agent. Instead, he was signed to a relatively big deal that set expectations for him to be one of the better left tackles in the NFL. He definitely lived up to expectations in 2014.

In 2015, he will be expected to continue to play at a high level while playing a greater role in the running game. His role in the running game should increase because the Cardinals are now built to run more to the left. A major reason for that is the addition of Mike Iupati.

Mike Iupati

Iupati was the team's biggest addition in free agency this offseason. He signed from the division-rival San Francisco 49ers after establishing himself as an All-Pro caliber player. Like Veldheer, Iupati is an established player who is still in his prime.

Over five years with the 49ers, the 28-year-old left guard started 75 games. It could be argued that he was the best guard in the NFL for a stretch early in his season, but various injuries affected his ability on the field over the past two years.

Despite playing through those injuries, Iupati was still playing to the high expectations that come with being a first-round pick.

His value to the Cardinals will primarily come in the running game. He is a versatile, mauling guard who can pull in either direction and advance to the second level if asked. His movement ability is very impressive but should be given even more credence when considering his size and power in tight situations.

Iupati is listed at 6'5" and 331 pounds. To put that in some context, Veldheer is a huge body outside of him, and Veldheer is listed at 6'8" and just 321 pounds. Both players are mammoths, and neither carries much negative weight when it comes to run blocking.

Having such an imposing athlete who can maul over defensive linemen at the line of scrimmage and escape to every area of the field to still be effective is a great asset for any offense. It is the kind of benefit that keeps a running game unpredictable.

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On this play, Iupati shows off great comfort as he pulls past the outside shoulder of his left tackle with impressive speed. However, once in open space he has the difficult task of engaging his assignment while reversing his momentum to reset on his outside shoulder.

The veteran guard makes this appear easy as he seals the edge, allowing Frank Gore to run toward the left sideline unopposed.

Iupati and Veldheer as a combination on the left side of the offensive line should create major issues for any defenses that are attempting to use undersized pass-rushers to attack the quarterback's blindside. Undersized rushers going against mammoth run-blockers are always more likely to favor the offense.

While Veldheer and Iupati can form an impressive combination on one side of the line, Iupati and Jonathan Cooper could prove to create an even more impressive combination as the team's starting guards.

Jonathan Cooper

Cooper was a first-round pick back in 2013. Not only was he Keim's first-ever draft pick, he was also the rare interior offensive lineman to go in the top 10 of a draft. He was selected seventh overall, ahead of Chance Warmack, who went 10th overall.

Warmack and Cooper have not lived up to their huge expectations as guards going that high in the draft, but judging Cooper on his play alone seems insincere.

The 25-year-old's career was immediately derailed by injury. During just the third preseason game of his career, Cooper suffered a severe leg break that would cost him his rookie season. He was slow in returning from that injury before turf toe limited him at the start of his second season, and a wrist injury ended it prematurely.

Between those injuries, Cooper was able to start just two games. His career to this point equates to just 189 snaps in the regular season. There is no possible way to evaluate what Cooper can do on this level because he simply hasn't been exposed enough.

His incredible athleticism can be traced back to his college tape, though. That athleticism is what made him appealing to the Cardinals and Arians' running scheme that asks his guards to pull on a regular basis.

That athleticism is also what keeps his promise alive at this point of his career. If Cooper can realize even a portion of his potential, he should be a quality starter for the Cardinals. If he can live up to the expectations coming out of the draft, he and Iupati will become a major force to be reckoned with.

At the very least, Cooper appears to be healthy and in pole position to win the starting job at right guard this year, via Adam Green of ArizonaSports.com: "I'm excited about it, I feel pretty good...I've been working at it in the offseason...Even just the mental space of switching over positions and understanding if I put in the work, I can do it."

Arians affirmed Cooper's optimism, "He's a natural athlete so it doesn't matter right side, left side. I'll go in and watch the tape, but he's been extremely -- he's got a smile on his face a lot, that's a good thing...I think he appreciates being healthy."

Even though a healthy Cooper is still an unknown, he is now in position to be the team's fourth- or fifth-best starter rather than a lynchpin of the unit. Considering that and his stock coming out of the draft, it's very easy to be excited about his potential this season.

It may be two years later than planned, but the Cardinals won't view it as too late if Cooper breaks out this season.

D.J. Humphries

The Cardinals have three first-round picks on their offensive line after adding two this offseason. Unlike Iupati though, D.J. Humphries was selected by the franchise itself.

Keeping with the theme, Humphries is 6'5" and 307 pounds. He relied on his athleticism rather than refined technique to be effective against college athletes. That may not work as expected early in his NFL career. He should be able to start for the Cardinals and be a viable starter but will need help to be above average.

The coaching staff will need to work with Humphries to improve his hand placement and technique both in space and in tight. If they can make minor alterations to his approach, he should be able to become an above-average starter from the beginning of his career.

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By switching over to the right side of the line and landing on a unit that boasts multiple talented, versatile pieces around him, Humphries should be able to carry out simplified assignments as a rookie. He can advance to the second level in the running game, but he shouldn't ever be asked to pull in either direction.

Eventually Humphries could be developed into that kind of offensive tackle, but there is no real need for him to be one in 2015.

What will also aid Humphries is the expected development of tight end Troy Niklas. Niklas barely played as a rookie, and when he did he was unimpressive. However, he has the size and talent to be a very effective run-blocking tight end. If he can establish himself ahead of Darren Fells, Humphries should benefit.

Having a high-quality tight end to double-team defensive linemen with or simply consume space when releasing into routes can make an offensive tackle's job much easier.

Health and inexperience are not in Niklas favor, but the soon-to-be 23-year-old tight end has the talent to be a difference-maker almost as an extension of the offensive line. Arians has a good history with blocking tight ends, and his offense has always heavily featured that kind of player. 2015 should be no exception.

There are obvious questions for the Cardinals offensive line that can only be answered once the season begins. However, the individual talent makes the unit a very compelling one on paper. Even with the prospect of starting Ted Larsen at center, the Cardinals are in much better shape now than they were in 2013 when Keim took over.

You don't even need to go back that far to feel like the team has made major strides.

Just last year the Cardinals ranked 23rd in DVOA. The natural reaction to that below-average ranking is to blame the turmoil that was endured at the quarterback position. However, the Cardinals ranked 19th passing the ball and 30th running the ball.

Running the ball has been a repeated issue for the Cardinals over the years. They ranked 25th in DVOA during the 2013 season and 32nd in 2012.

Even without knowing who the team's primary back will be, the Cardinals can realistically expect to at least be an average rushing offense in 2015. Quality offensive line play has a major effect on the effectiveness of a team's rushing game.

Only great running backs can consistently produce in spite of their offensive lines, but most backs who reach the professional level can be effective when paired with a strong offensive line. Whether it's Andre Ellington, Stepfan Taylor, David Johnson, Kerwynn Williams or a combination, the running game in Arizona will be better next season.

A better running game with a healthy Palmer and that group of wide receivers makes for a very exciting group of personnel in the desert.