By Dan Durkin-

(CBS) Jim Caldwell was hired by the Detroit Lions for a few reasons — to help unlock the potential of quarterback Matthew Stafford and the fact he is the anti-Jim Schwartz.

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The mild-mannered Caldwell was the quarterbacks coach in both Indianapolis and Baltimore when Peyton Manning and Joe Flacco, respectively, won Super Bowls. Considering the $82 million that Detroit has already invested in Stafford — and potentially more given he’ll only be 29 when his current contract expires in 2017 — it must find a way to maximize the return on their investment.

Under Schwartz, the Lions were the team you loved to hate. They played aggressively, bordering on dirty, to the echo of the whistle. Undisciplined play became the norm, but so did late-season slides.

In Schwartz’s final two seasons in Detroit, he compiled a 2-14 mark in the second half of the season. As the cliche goes, it’s not about how you start, it’s about how you finish. Schwartz’s inability to finish finished him in Detroit.

Caldwell faces a similar challenge this season. After jumping out to a 7-2 start, the Lions have lost back-to-back games in lackluster fashion. Granted, the Lions played the two teams with the best record in football, the 9-2 Arizona Cardinals and New England Patriots, but their offense hasn’t scored a touchdown in 22 possessions. Injuries have certainly played a part in their recent struggles, but there are some other troubling trends developing in Motown.

With the offensive line struggling to create movement on the defensive line, Detroit’s run game has come to a halt. Only twice this season have the Lions eclipsed the 100-yard mark. They rank 30th in the league in both yards per game (81) and yards per attempt (3.3).

Reggie Bush’s contributions have been minimized due to an ankle injury, and Joique Bell’s season-high rushing total is 85 yards. Consequently, opposing defenses have defended the run with seven-man fronts, which allows them to keep seven defenders back in coverage to defend the Lions’ purportedly potent passing attack.

Injuries along the offensive line have played a part, and they may have even more to deal with Thursday against the Bears. Right guard Larry Warford (knee) has been out for several weeks. In his rookie season last year, Warford developed into not only the Lions’ best offensive lineman but also one of the league’s most complete players at his position.

Complicating matters, left tackle Riley Reiff (the Lions’ first-round selection in 2012) is also dealing with a knee injury, and his status for Thursday seems to be in doubt. This would thrust undrafted rookie Cornelius Lucas into action on Stafford’s blindside.

The injuries haven’t been limited to the offensive line. The league’s most dynamic receiving threat — Calvin Johnson — has been hampered by an ankle injury. At this point last season, “Megatron” had 12 touchdown catches. This season, he has three.

Johnson is unparalleled in size, speed and catching radius. He has the ability to win jump balls just as easily as he can use his long strides to stack on top of defensive backs. Given how generous the Bears’ secondary has been this season, it’s hard to imagine Johnson not finding success in Thursday’s game.

In Johnson’s absence, Stafford has developed a chemistry with free-agent signee Golden Tate. For years, the Lions have repeatedly missed with their attempts to find a complementary receiver to win single-coverage matchups as defenses roll their coverage to Johnson’s side of the field. Tate has blossomed in Detroit, ranking fifth in the league in targets (106) and sixth in receiving yards (1,047).

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The Lions brought in Joe Lombardi from New Orleans to coordinate their offense. Lombardi learned from Sean Payton, who runs a personnel-driven system that schemes advantageous matchups with a variety of personnel groupings, formations and pre-snap shifts and motions.

The Lions are still finding their way within the system, as deeper passing routes have been slow to develop and the rotation of personnel may be hampering them.  They may be best served to keep their core players together in their preferred 11 personnel grouping and attack from that.

Stafford has thrown an interception in six of his last seven games. Footwork remains a struggle for Stafford, but once he learns to tie his footwork together with the route combinations, the offense will settle in. He still seems to be at his best when things break down, as opposed to letting plays develop as designed.

Defensively, the Lions are the league’s best. They don’t do it with exotic looks; they do it with execution. They’re a fairly static 4-3 defense that plays a lot of split-safety shells (Cover-2 and Cover-4), and they simply suffocate opponents with their stout defensive line, led by defensive tackle Ndamukong Suh.

Suh is the engine to the Lions defense. He’s brutally strong at the point of attack and has elite first-step quickness to dictate the engagement. By pressing the pocket from the inside, he forces double teams, which plays well with the wide-nine alignments that defensive coordinator Teryl Austin deploys on the edge.

With their defensive ends lined up wide (outside shoulder of the tight end, even if no tight end is present), they create a direct, sharp angle to the quarterback. This forces offensive tackles to accelerate their kick slide and prevents a double team from the guard.

The Lions have a deep defensive line rotation, which features eight solid contributors. Ziggy Ansah has developed into the end they envisioned when the used the fifth overall selection on him in the 2013 draft. Ansah is a raw prospect but plays with leverage and already has the size and functional strength to match.

Opponents are averaging a league-low 71 rushing yards per game against Detroit, and its linebacker play has a lot to do with it. Weak-side linebacker DeAndre Levy has developed into a premier run defender who keeps his shoulders low as he quickly fits his gap in the run game.

The Lions are also fond of “big nickel” packages, which use three safeties (Glover Quin, James Ihedigbo and Isa Abdul-Quddus). As such, they don’t lose out in the run game when they substitute a defensive back for a linebacker in nickel packages.

The Bears have struggled against teams who “zone them out,” which is exactly how the Lions play defense. Thus, if the Bears’ offensive line is unable to handle the Lions’ four down linemen, it will be another offensive struggle for Chicago.

This is a must-win game and a true-up for the Bears (5-6) to find out where they really stand. For the Lions (7-4), it’s an opportunity to snap their losing streak and keep themselves in the thick of the playoff hunt.

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