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A great quarterback can inspire a team to incredible heights in the NFL. Conversely, instability at the sport's most important position can trigger unintended and very undesirable consequences.

No one knows that better than Ken Whisenhunt.

The crowing achievement of the Arizona Cardinals head coach's career -- and the franchise he represents -- took place four years ago, when a resurgent Kurt Warner carried one of the league's perennial also-rans to the brink of its first-ever Super Bowl victory and nearly ended an epic championship drought that's lingered since 1947. With Warner still on top of his game the following season, Whisenhunt's Cardinals won 10 regular-season contests and claimed a second straight NFC West title.

Warner retired following that 2009 campaign, and Arizona's title hopes departed along with him. The Cardinals have gone a substandard 13-19 in the two years since the affable signal-caller called it a career, while auditioning a merry-go-around of mediocre passers along the likes of Derek Anderson, Max Hall, Kevin Kolb and John Skelton.

Arizona was able to ride the unexceptional combo of Kolb and Skelton to a somewhat respectable 8-8 finish last year, and after an unsuccessful play at Peyton Manning during this offseason, decided to roll the dice on the pair and hope one would emerge as a viable, or at least passable, option.

Judging by the early returns, it's a gamble that might not pay off for the Cardinals as they strive to get back into the playoff hunt in 2012 following back-to-back misses. Neither Kolb nor Skelton distinguished himself during the preseason, forcing Whisenhunt to delay his decision on a Week 1 starter until just days before the first game.

Whisenhunt ultimately settled on Skelton, who did display plenty of grit in leading Arizona to a 5-2 record in seven fill-in starts for an injured Kolb, the Cardinals' intended answer under center after the team traded talented cornerback Dominique Rodgers-Cromartie and a 2012 second-round draft pick to Philadelphia to acquire the then-hot commodity last August.

"We put a lot of time and effort in making the decision, and we feel like it's the right decision," Whisenhunt quipped.

While Skelton's summer performance was hardly awe-inspiring -- and his hold on the starting job will be tenuous if he doesn't succeed -- the Cardinals still believe they're capable of making a significant splash in the NFC West after their strong finish to 2011.

And there are reasons for such optimism.

For one, Arizona boasts one of the game's premier receivers in six-time Pro Bowl participant Larry Fitzgerald and the makings of a potent rushing attack fueled by two highly skilled but injury-prone backs, Beanie Wells and Ryan Williams. And the Cardinals closed out the 2011 slate with a furious flourish, winning five of their last six outings behind an overlooked defense that held the opposition under 200 net passing yards in four of those contests.

The unit returns all but one starter from last year's group, including such high-impact performers as safety Adrian Wilson, linemen Calais Campbell and Darnell Dockett, underrated inside linebacker Daryl Washington and freakishly athletic young cornerback Patrick Peterson.

"It's knowing the defense can work, because of where we finished last year," said Campbell in explaining the Cardinals' rosy outlook. "When we are jelling and we do it right, the offense has no chance. They only make plays when we make mistakes and we haven't made a lot of mistakes lately. Our confidence is high. I can't wait to get in there that first game."

Below we take a capsule look at the 2012 edition of the Arizona Cardinals, with a personnel evaluation and prognosis included therein:

2011 RECORD: 8-8 (2nd, NFC West)

LAST PLAYOFF APPEARANCE: 2009, lost to New Orleans in NFC Divisional Playoff

COACH (RECORD): Ken Whisenhunt (40-40 in five seasons)

OFFENSIVE COORDINATOR: Mike Miller (second season)

DEFENSIVE COORDINATOR: Ray Horton (second season)

OFFENSIVE STAR: Larry Fitzgerald, WR (80 receptions, 1411 yards, 8 TD)

DEFENSIVE STAR: Adrian Wilson, S (65 tackles, 1 INT)

2011 OFFENSIVE TEAM RANKS: 19th overall (24th rushing, 17th passing), 24th scoring (19.5 ppg)

2011 DEFENSIVE TEAM RANKS: tied 18th overall (21st rushing, 17th passing), 17th scoring (21.8 ppg)

KEY ADDITIONS: RG Adam Snyder (from 49ers), RT Bobby Massie (4th Round, Mississippi), CB William Gay (from Steelers), WR Michael Floyd (1st Round, Notre Dame), C Rich Ohrnberger (from Patriots), OLB Quentin Groves (from Raiders), S James Sanders (from Falcons)

KEY DEPARTURES: LT Levi Brown (out for season), RG Rex Hadnot (to Chargers), RT Brandon Keith (free agent), OLB Joey Porter (retired), CB Richard Marshall (to Dolphins), RB Chester Taylor (free agent), WR Chansi Stuckey (released), OG Floyd Womack (free agent), OG Deuce Lutui (to Seahawks), S Hamza Abdullah (free agent), S Sean Considine (to Ravens)

QB: Skelton (1913 passing yards, 11 TD, 14 INT) doesn't have the statistics associated with a high-end quarterback, having completed under 53 percent of his passes in 13 career games (11 starts) and throwing more interceptions than touchdowns last year, and his accuracy remained spotty in his preseason appearances. The third-year pro does own a big arm, however, and is cool under pressure, as evidenced by the four fourth-quarter comebacks he engineered in 2011 in addition to directing late game-winning drives in two other victories. Kolb (1955 passing yards, 9 TD, 8 INT) possesses better marksmanship but has developed an unwanted reputation for being skittish in the pocket and extremely brittle, having missed seven games due to a concussion and a sprained toe last season while also forced to the sidelines by a head injury with the Eagles in 2010. While both have had their moments, it still shapes up as far from an ideal situation. Rookie Ryan Lindley may have the inside track on holdover Richard Bartel (1 TD, 1 INT) for the No. 3 spot after being taken in the sixth round of April's draft. Like Skelton, the San Diego State alum has plenty of arm strength, but is a limited athlete and developmental project who'll need to work on his touch.

RB: Whoever ends up taking the majority of the snaps at quarterback could be aided by a potentially devastating one-two backfield punch of Wells (1047 rushing yards, 10 TD, 10 receptions) and Williams. That is, if either can stay on the field. Williams was a durability risk entering last year's draft, when the Cardinals took him in the second round, then proceeded to miss his entire rookie campaign with a torn patellar tendon in his knee. The main reason why Arizona drafted him in the first place was Wells' history of nagging injuries that dated back to his college days at Ohio State. Wells did admirably battle his way through a sore knee to post his first 1,000-yard season in 2011, but missed some time in camp while recovering from a procedure to rectify the problem. Williams did look very good in limited action during the preseason, and his elusiveness in the open field should make him an excellent complement to the power-based Wells if he's indeed all the way back. The diminutive LaRod Stephens-Howling (167 rushing yards, 13 receptions, 2 TD) is a fine receiver who averaged an eye-popping 18 yards per catch as the third-down back last year, and he'll reprise those duties in addition to continuing to be the main kick returner. Fullback Anthony Sherman (8 receptions) can also catch the ball and fared pretty well as a blocker, particularly in pass protection, as a rookie this past season. The injury concerns to the top two have necessitated carrying a fourth tailback on the roster, with 2011 practice-squad member William Powell making the cut after an outstanding preseason.

WR: Last year's quarterback shuffle didn't have much of an effect on the production of the incomparable Fitzgerald (80 receptions, 1411 yards, 8 TD). Although the graceful wideout's 80 catches were his lowest since 2006, his yardage total was the second-highest of his brilliant eight-year tenure in the desert after averaging a personal-best 17.6 yards per grab. The fantasy football superstar has averaged 93 catches, nearly 1,300 yards and 10 touchdowns over the past five seasons and missed only one game over that superlative stretch. No. 2 receiver Andre Roberts (51 receptions, 2 TD) often struggled with his route-running and separation skills during his first trial as a starter last season, but started to come on near the end of the year and brought that improvement into camp, holding off more-talented 2012 first-round draft pick Michael Floyd to keep the job. Floyd will be brought along slowly in his debut after not yet earning the coaches' trust, but the former Notre Dame standout could be a factor in the red zone with his 6-foot-3, 225-frame and certainly has the ability to form a very dangerous duo with his mentor Fitzgerald down the road. Early Doucet (54 receptions, 5 TD) was re-signed to a two-year deal in March after finishing second on the team in catches and receiving yards (689) during a mild breakout as the slot receiver, while the Cardinals may have mined a future gem in rookie LaRon Byrd, an undrafted college free agent with great size who impressed in the preseason.

TE: The Cardinals shouldn't lack options at a tight end spot that ranks as one of the team's deepest positions. Veteran Todd Heap (24 receptions, 1 TD) has logged nearly 500 catches over an 11-year career spent predominantly with Baltimore, but the 32-year-old has been injury-prone and less of a downfield threat in his advancing age and could be close to giving way to promising sophomore Rob Housler (12 receptions). The 2011 third-round pick can run a sub-4.5 second 40 yard dash and is more refined this year after contributing sparingly as a raw rookie, making him another possible weapon in a receiving corps that holds a lot of upside. Heap is still a reliable possession target when healthy, while seventh-year pro Jeff King (27 receptions, 3 TD) brings a solid all-around game to the table as a willing blocker who can also help out the quarterbacks. With Arizona leaning to more of a run-based approach this season, he'll again have an important role. Fellow returnee Jim Dray offers little as a pass-catcher, but can block and make a mark on special teams.

OL: While Whisenhunt clearly has some anxiety over his quarterbacks, a front wall that allowed the second-most sacks (54) in the league last season is by far the most worrisome department on the team. The situation grew even more dire when starting left tackle Levi Brown tore his triceps in the third preseason outing and was placed on season-ending injured reserve, leaving the most important position on the line now in the hands of D'Anthony Batiste, a journeyman who hasn't started a game since 2007. The Cardinals do have a more experienced alternative in 10th-year vet Jeremy Bridges, who owns 55 career starts and has filled in capably at left tackle for Arizona in the past. However, he didn't have a good camp and was beaten out by rookie Bobby Massie (Mississippi), a fourth-round choice in April's draft with the highest ceiling of the candidates, for the right to be the regular on the right side. There's far more stability along the interior, where center Lyle Sendlein has been a rock in beginning every game over the past four years and left guard Daryn Colledge is also both seasoned (92 career starts) and durable, though the 2011 free-agent addition is coming off somewhat of a disappointing year after being lured away from Green Bay with a big contract. Arizona turned to the market as well this offseason to bolster right guard, inking ex-49er Adam Snyder to a five-year deal. His arrival gives the unit more flexibility, having also seen time at right tackle and center during his career. Former Patriot Rich Ohrnberger will serve as Sendlein's main backup, while a couple of projects were added in this year's draft in Washington guard Senio Kelemete (5th Round) and Boise State tackle Nate Potter (7th Round).

DL: Arizona is now well set at two of the three positions along the defensive line with the relentless Dockett (51 tackles, 3.5 sacks) manning under tackle and the physically imposing Campbell (72 tackles, 1 INT) coming off a monster season in which the 6-foot-8 left end amassed a team-best eight sacks and swatted down 10 passes while also being a force against the run. For his efforts, the 26-year-old was rewarded with a five-year contract with $31 million in guarantees in May. Dockett is a disruptive pass-rusher in his own right who's made three Pro Bowls over the last four years, and still sports a quick first step despite turning 31 in May. Nose tackle Dan Williams (20 tackles), a first-round pick by the Cards in 2010, has showed flashes of becoming a stout run-stopper in the middle, but has battled weight and injury issues over his first two years in the league. If he improves, this area can go from good to great. The reserve ranks remain unchanged with still-capable graybeard Vonnie Holliday (16 tackles) brought back for a 15th NFL season to re-join 10th-year tackle Nick Eason (12 tackles, 1 sack) and young backup nose man David Carter (16 tackles, 1 sack).

LB: Getting a consistent rush from the edge was a problem for the Cardinals early last year, as the declining duo of Joey Porter and Clark Haggans weren't getting it done, but improvement came after then-rookie Sam Acho (40 tackles, 7 sacks) replaced an injured Porter in midseason and third-year man O'Brien Schofield (37 tackles, 4.5 sacks) began seeing more time down the stretch. The pair combined for 11 1/2 sacks and six forced fumbles, and the team feels they're capable of doing even more as full-time players in 2012. Washington (107 tackles, 5 sacks, 2 INT) is also an effective blitzer from the inside in addition to possessing exceptional coverage traits and the speed to make plays all over the field. He's quickly becoming the headliner of a contingent that also includes the steady Paris Lenon (93 tackles, 3 sacks) alongside him. Ex- Eagle Stewart Bradley (31 tackles) was supposed to push the aging Lenon into a backup capacity after originally signing a five-year, $25 million contract prior to last season, but had trouble getting up to speed in coordinator Ray Horton's defense and was mostly an afterthought. He still gives the team a quality backup and special-teams contributor after agreeing to a pay cut in the spring. Reggie Walker (16 tackles) is also valued for his work on the coverage units, while Quentin Groves (24 tackles with Raiders) was signed in the offseason to further bolster that area and be the top outside reserve.

DB: Arizona's pass defense got markedly better over last season's second half, in part due to the upgraded pressure from the front seven but also because of Peterson (64 tackles, 1 sack, 2 INT) resembling more of the shutdown corner the team envisioned he'd become when making the reigning Thorpe Award winner the fifth overall choice of the 2011 draft. The well-built LSU product endured a rough beginning to his pro career but really emerged over the final stages, and the Cardinals are confident he'll be able to routinely shadow No. 1 receivers in his second year. The club did lose Richard Marshall, another factor in the secondary's resurgence, to Miami in free agency, but countered by signing former Steeler William Gay (61 tackles, 2 INT, 13 PD) to take over opposite Peterson. The five-year vet is very familiar with the scheme of Horton, a onetime disciple of Pittsburgh defensive guru Dick LeBeau, and offers plenty of experience in covering the slot as well. Arizona also welcomes the return of Greg Toler, a 13-game starter at corner in 2010 who missed all of last year with a torn ACL. He's the favorite to play the nickel if proven to be fully recovered, though the staff also has faith in undersized holdover Michael Adams (41 tackles) and has high hopes in the future for rookie Jamell Fleming, a third-round pick out of Oklahoma with strength and good instincts. While Peterson may be the backfield's most talented member, it's unquestioned leader is Wilson (65 tackles, 1 INT, 17 PD), a five-time Pro Bowler with a vocal presence and an intimidating style who plays the run like a linebacker and rarely gets caught out of position. He'll team again with free safety Kerry Rhodes (34 tackles, 2 sacks), a seven-year starter with the Jets and Cards who's a proven last line of defense. Depth on the back end is fine with veteran pickup James Sanders (41 tackles with Falcons) joining fourth-year man Rashad Johnson (50 tackles), while 2012 sixth-rounder Justin Bethel (Presbyterian) is a special teams whiz who blocked nine kicks in college.

SPECIAL TEAMS: While Peterson showed himself to be an asset on defense as a rookie, his impact in the return game was even more profound. The athletic youngster tied an NFL single-season record by taking four punts for touchdowns while averaging a splendid 15.9 yards per runback, second-best in the league. Stephens-Howling (23.8 ypg) is no slouch on kickoffs either, having averaged over 25 yards per return and scoring three times over his three seasons. Punter Dave Zastudil was brought back after averaging a respectable 45.2 yards per boot and pinning 24 attempts inside the 20-yard line, as was Jay Feely despite an off year for the usually reliable kicker. The well-traveled 36- year-old made good on just 19-of-24 field goal tries, his lowest percentage since 2004, but was 24-of-27 on three-pointers the previous year. Also retained was dependable long snapper Mike Leach, entering his 13th season in the league and fourth with the Cardinals.

PROGNOSIS: At first glance, the Cardinals don't appear to be all that different than the team that went 8-8 a year ago, with the roster undergoing relatively little turnover in the offseason. And the fact that Skelton was able to win games in his extended 2011 audition could be used to counter the prevailing opinion that Arizona is bound for doom in the coming months. A closer look, however, reveals that Peterson had a major hand in three of last year's victories with his special-teams scores, and opponents likely aren't going to be as willing to put the ball in the dynamic return man's hands this time around. All of the Cardinals' wins also came by seven points or less, and they may not be so successful in the close ones if Skelton or Kolb take their error-prone ways of the preseason into the games that count. And although the offensive line wasn't good last season, it wasn't in near the shambles of it's current state. In a land where the temperature is always hot, the seat Whisenhunt is sitting on may get awfully toasty if Arizona's numerous questions on offense can't be resolved.