By Dan Durkin-

(CBS) More than any other professional sports league, success is fleeting in the NFL.

Just last season, the Carolina Panthers reeled off 11 wins in their final 12 games to end a five-year playoff drought and earn a first-round bye and a home playoff game.

Coach Ron Rivera’s blueprint of defensive success was reminiscent of his time in Chicago — eliminate the run to make teams one-dimensional and successfully rush with four while keeping seven sets of eyes on the quarterback. The results were remarkable. The Panthers held teams to 20 points or fewer in 13 of 16 games and didn’t allow a first-half touchdown until Week 10.

They eventually lost to the 49ers in the divisional round. Their pedestrian group of wide receivers and leaky secondary were exposed, but by any measure, the 2013 Panthers exceeded all expectations, and their arrow was seemingly pointed up.

However, the 2014 offseason was cruel for the Panthers.

Two retirements (left tackle Jordan Gross and left guard Travelle Wharton), a cap casualty (receiver Steve Smith) and an arrest (defensive end Greg Hardy) had a devastating effect on the roster.

Tracing the timeline backward, curious contracts penned by ex-general manager Marty Hurney are the root cause for the pinch the Panthers found themselves in.

From extending quarterback Jake Delhomme’s contract without offset language to spending $43.5 million guaranteed on running backs DeAngelo Williams and Jonathan Stewart — while the rest of the league was devaluing the position — the Panthers were using BlackBerries in an iPhone world.

Numerous draft classes bore no fruit, the team never found a complementary wide receiver to take advantage of the coverages that were rolled to Smith’s side of the field and they routinely struck out on prospects in the trenches.

Under Hurney, the Panthers did, however, connect on back-to-back first-round picks in selecting Auburn quarterback Cam Newton and Boston College linebacker Luke Kuechly. Both players are dynamic, game-changing talents who serve as the team’s building blocks for the future.

Hurney was eventually fired, and Dave Gettleman has the unenvied task of undoing what’s already been done and rebuilding the team around his young superstars.

The Panthers’ previous formula of running the ball on offense and stopping the run on defense has faltered thus far. They’re gaining just 3.1 yards per attempt on offense, which is second-worst mark in the league, and they’re giving up 5.7 yards per attempt on defense, which is the worst mark in the league. Like the Bears, they’re 2-2 heading in Sunday’s game.

Offense

Carolina offensive coordinator Mike Shula runs a ground-based scheme that favors traditional I-formation power, one-back power and inside/outside zone runs primarily out of their 11 (one running back, one tight end) personnel grouping, but they also throw in 12 and 21 groups.

The success Newton had early on in his career was predicated on his running prowess. The zone-read package that was used under previous offensive coordinator Rob Chudzinski still exists, it’s just been de-emphasized under Shula.

Part of that decision is certainly to protect Newton, who had offseason ankle surgery and started the season with cracked ribs. Newton’s maturation as a passer is evident, as he’s displaying more of a willingness to stand in the pocket to let route combinations to materialize, opposed to his previous tendency to tuck the ball and run when his primary read wasn’t immediately open.

Through three games, Newton has completed nearly 64 percent of his passes, has yet to throw an interception and boasts a passer rating of 98.2.

Newton still needs refinement, as his lower body framework can be loose at times, which leads to passes sailing on him. To compensate, the Panthers have targeted bigger-bodied guys for Newtown.

This past May, they hit on their first-round selection of Florida State wide receiver Kelvin Benjamin. At 6-foot-5 and 240 pounds, Benjamin is a massive physical specimen with a huge catching radius. Benjamin needs to clean up his route running and will occasionally drop catchable passes, but he leads the Panthers in every major receiving statistic.

Ex-Bear Greg Olsen is Newton’s second favorite target, who, like Benjamin, is a hybrid wide receiver/tight end. While Olsen struggles as an in-line/Y tight end, he’s effective as a move tight end/H over the middle of the field, where he’s a mismatch against safeties and linebackers.

The Panthers’ undoing this season has to do with their sieve-like offensive line and the rash of injuries to their running backs.

Other than Ryan Kalil, the Panthers are at a disadvantage at every other position along the line. With minimal talent in the pipeline, they were ill-prepared to soften the blow of losing the left side of their offensive line.

Left tackle Byron Bell took over by default, sliding over from the right side, but his heavy feet cause him to give up the edge in pass protection sets, and he struggles to get movement in the run game. Right tackle Nate Chandler — a former defensive tackle — hasn’t fared much better, giving up eight hurries and three sacks.

With no push up front and a banged-up backfield, the Panthers have just nine runs of five-plus yards this season. Injuries to DeAngelo Williams (ankle), Jonathan Stewart (knee) and Mike Tolbert (leg), may force recently signed Chris Ogbonnaya and undrafted rookie Darrin Reaves to get the lion’s share of the carries this Sunday.

The lack of offensive talent is casting a shadow on what’s been an impressive season for Newton. With the threat of Newton running minimized, defenses are playing more man coverage without needing a spy for Newton, as with few exceptions, receivers are struggling to separate from coverage.

Defense

The Panthers have depth along their defensive front, but the loss of Hardy has forced defensive coordinator Sean McDermott to bring more blitzes from the back seven, leaving an already vulnerable secondary even more exposed.

The interior of the defensive line is stout. Kawann Short has been their most effective pass rusher, collapsing the pocket from the inside. Star Lotulelei can anchor against the run, but the lack of an edge rusher allows offenses to double inside at the point of attack.

Save for a few flashes from Mario Addison, they don’t put enough pressure on opposing quarterbacks, who are averaging a 95 passer rating. Charles Johnson, who was the league’s highest-paid defender in 2011, is a non-factor, and second-round pick Kony Ealy has struggled to disengage from blockers.

At the second level, the Panthers have one of the better nickel linebacker combinations of Kuechly and Thomas Davis. Last week, Davis was inactive due to a hip and hamstring injury, but his recovery from three ACL reconstructions is a remarkable story in itself.

As the Panther struggle to fit gaps against the run and generate pressure on opposing quarterbacks, their secondary is a collection of mismatched pieces.

Two familiar faces and former foes man the top of the defense — free safety Thomas DeCoud and strong safety Roman Harper. DeCoud is the Panthers’ most responsible player in coverage, but Harper is purely a run-support player.

On the perimeter, the Panthers are searching for answers. Josh Norman will replace Melvin White at right cornerback this weekend, while Antoine Cason stays at left cornerback. Collectively, the secondary has given up eight touchdowns while generating only three interceptions. Against the Bears’ potent passing attack, this group could be in for a long afternoon this Sunday in Charlotte.

The saving grace for the Panthers may be the division they play in. No defense is being played in the NFC South, but will the Panthers be able to generate enough offense to capitalize? It seems as though this team is at least a year away from contending for a playoff berth.

Dan Durkin covers the Bears for CBSChicago.com and is a frequent contributor to 670 The Score. Follow him on Twitter at @djdurkin.