How does a 2-1 team facing an 0-3 team at home end up as a 2.5-point underdog according to Vegas?

That's what happens when the most important player to your offense goes down to injury and you have to replace him with Michael Vick.

With Ben Roethlisberger out for the next few weeks due to a knee injury suffered in Week 3 against the Rams, the Steelers offense gets their first test as they face their visiting division rivals the Baltimore Ravens this Thursday night.

So will the Steelers offense step up in Big Ben's absence or will the Ravens end their worst start in franchise history when they travel to Pittsburgh?

The Pre-Game Rundown

Following a defeat against the New England Patriots to open the season, the Steelers took their frustration out in Week 2 on the San Francisco 49ers. Playing without Pro Bowl center Maurkice Pouncey, all world running back Le'Veon Bell, and touchdown maven Martavis Bryant, the team still found a way to ring up San Franisco's defense for 453 total yards and 6 offensive touchdowns (3 passing and 3 rushing) to the tune of 47 points.

And with the return of their elite, third year tailback Bell from a two-game suspension in Week 3, it looked as if this offense would be almost impossible to stop. Almost was right.

In what would turn out to be a pyrrhic victory, the Steelers lost Roethlisberger for the next four to six weeks to a sprained MCL after Rams safety Mark Barron fell into his leg.

All eyes will be on backup quarterback Vick to see if he can keep this offense on track. However, early indications are far from promising; last week the offense managed just 60 total yards in the 20 minutes of gametime Vick played in relief of Big Ben. While some may argue that Vick may find more success after practicing with the first team this week, with the shortened prep week and his less-than-stellar 2014 performance, I won't be holding my breath.

Last season Vick managed just 135 yards per game and 3 passing touchdowns and an interception in his 3 starts with the Jets. This resulted in a -0.23 Passing Jake Locker (-0.13), Robert Griffin III (-0.15), and Blake Bortles (-0.18).

For those unfamiliar, NEP is our signature metric here at numberFire. If you contribute to your team's chances of scoring above expectation you receive a positive NEP, and a negative score when you do the opposite. 

To limit Vick's responsibilities in moving this offense, the team is expected to lean heavily on Bell both in the running game and in the passing game and the team could also look to use resurgent veteran tailback DeAngelo Williams more as well. Williams seems to have found the Fountain of Youth in Pittsburgh, averaging an impressive 5.0 yards per carry and 0.19 Rushing NEP per attempt over his 41 carries in Bell's absence.

It's clear that the Steelers defense will also need to step up like it did last Sunday if the team hopes to win without Big Ben. Following a poor showing to start the season, the team limited Nick Foles and the Rams offense to just 6 points on 268 yards of total offense. The question is whether or not we'll see more of the same on Thursday Night against Baltimore or if we'll once again see the same unit that surrendered an average of 312 yards, 3 touchdowns, and no interceptions over the first two weeks of the season.

And this tough task assigned to the Steelers defense will get even harder if they're once again without stud inside linebacker Ryan Shazier, whose shoulder injury has held him out since late last week.

Behind a sub-par defense, and an offense that lacks any reliable options beyond Steve Smith, the Ravens find themselves at 0-3 to start the season for the first time in franchise history.

The trade of defensive tackle Haloti Ngata to Detroit this past offseason has noticeably effected the Ravens ability to stop the running game. While this defensive unit ranked second in the league last season against the run according to our advanced metrics, this team ranks just 19th over the season's first three games.

And the Ravens haven't had much luck stopping the pass either.

The secondary took a heavy blow when safety Matt Elam was ruled out for the season this past August with a torn bicep. Couple an already leaky pass defense with a weakened pass rush following outside linebacker Terrell Suggs' torn Achilles and what you have is a recipe for disaster.

The Ravens defense currently sits as just the 15th most efficient squad according to our strength of schedule-adjusted Defensive NEP metrics.

On the offense, the team is looking for someone to step up and shoulder the load next to their star wideout in Smith. With Torrey Smith now with the Niners and heir apparent to his role, rookie Breshad Perriman, unable to stay healthy, Steve Smith has been forced to play far more snaps and a far bigger role than head coach John Harbaugh originally intended.

Over the first three weeks of the season, Steve Smith has accounted for 25 receptions for 349 yards and 2 touchdowns on 40 targets.

Following Crockett Gillmore's ascent to become the number two option in this passing game with his impressive 5-reception, 88-yard, and 2-touchdown performance against the Raiders, Joe Flacco will need to find a new option to throw to this Thursday as reports suggest Gillmore will likely be ruled out with a calf injury.

This leaves the door open for rookie tight end Maxx Williams to step up and perhaps step up into the pass catching role many expected him to inherit given his superb physical skills. However, sidelined by multiple injuries all throughout training camp, it will be interesting to see if Williams can quickly build chemistry with and earned the trust of his quarterback.

After giving the Ravens a surprise Pro Bowl-worthy performance last season -- amassing 1,266 rushing yards, 263 receiving yards, and 8 touchdowns in 14 starts -- starting running back Justin Forsett has been fairly pedestrian this season. Through three games this year, Forsett has managed just 124 yards on 39 carries (3.2 yards per carry) to go along with 12 receptions for 41 yards and no touchdowns. The question now is whether Forsett can rediscover his 2014 form under new offensive coordinator Marc Trestman or if Lorenzo Taliaferro -- who recently returned from a foot injury last week -- will begin to take on a larger workload due to Forsett's disappointing inefficiency.

So what can we expect when these two AFC North powers clash on Thursday Night Football?

The Ravens' Game Script

With Pittsburgh boasting a defense which ranks as the 9th most efficient unit against the run, but 23rd against the pass, expect Baltimore to attack Pittsburgh's weak cornerbacks.

Steve Smith has more than twice as many targets as the next man on the list (Forsett with 18). Expect that trend to continue as Smith will likely draw William Gay this week in coverage. The real question is whether someone will step up for the Ravens offense or if Smith will need to repeat his 13-reception, 187-yard, 2-touchdown performance in a loss against the Bengals last week.

The likely candidate for this would be rookie tight end Maxx Williams. Marc Trestman's version of the west coast offense is built on high percentage throws in the short passing game and the tight end has been looked to frequently in the Ravens offense this year. Crockett and Williams account for one-fifth of the 125 targets on this team already.

In the ground game, Forsett faces a tougher task than his passing game counterparts. While the passing defense has been fairly porous this season, the run game has been better than expected, with Pittsburgh's defense ranking 9th in Adjusted Defensive Rushing NEP per play after holding both the Niners and Rams running backs to fewer than 61 yards on the ground, each.

The Steelers' Game Script

Already hurting from injuries and suspensions, the Steelers must find a quick solution to their problems at quarterback during this short week of practice.

With the inefficient Vick under center, don't expect Antonio Brown to enjoy the same performances against Jimmy Smith and the Ravens secondary that he had over the first three weeks of the year. Though Brown currently ranks in the top five of the league in Reception NEP per target (1.18), he'll be hard-pressed to maintain this level of consistency in this contest.

While the Ravens currently rank 20th against the pass according to our advanced metrics -- with Smith himself just recently giving up a huge 10-reception, 227-yard, and 2-touchdown outing to Bengals wideout A.J. Green -- the question of whether or not Vick can effectively deliver the ball to his wideouts, including Brown, remains.

All this suggests that if the Steelers want to move the ball and keep their defense off the field, they'll need to do it with their ground game. With last year's second-leading rusher Bell ready to roll, and veteran Williams in place to spell him, the team should find success against a Ravens run defense that currently ranks 19th against the rush according to our schedule-adjusted metrics.

However, while the Steelers backfield won't have to contend with All Pro Terrell Suggs -- who is out for the season with a torn Achilles suffered in Week 1 -- what they will likely face are defensive fronts with eight-or-more men in the box due the lack of a passing game threat Vick poses.

Fantasy Football Implications

If Big Ben is the rising tide that lifts all boats, Vick may just be the wave that sinks all ships. With Vick's inaccuracy (he boasts a 53.8% completion rate over his last two seasons in Philadelphia and New York), coupled with the fact that this contest is a Thursday Night Football game -- which historically has negatively impacted the passing game -- it's tough to recommend anyone on the Steelers passing game for this contest.

Of course, Brown remains a must start in season-long fantasy leagues as he goes for his 36th straight game with at least 5 catches for 50 or more yards, but his reduced ceiling with Vick under center is causing me to shy away from him in daily leagues. And while I typically love the running game in Thursday Night Football thanks to the reliance of teams on simplified game scripts, with Vick under center, expect Bell and Williams to face stacked boxes all night as the Ravens dare the Steelers to beat them with the backup quarterback's arm.

With a juicy matchup against burnable cornerbacks and a the heavy volume of looks that will once again come his way, Smith is a must-start in this contest. Next to him in the passing game, a sneaky play may be tight end Williams. With Gillmore out and no clear number two receiving option, Williams may be able to take advantage of a defense that's yielded the third most points to tight ends through the first three weeks of the year in standard-scoring leagues.

If you're waiting for a breakout game for Forsett, keep waiting. With the Steelers presenting Baltimore with a number of exploitable matchups in the secondary, the Ravens may go pass heavy, at least early on in this game. And while the Ravens may feature Forsett and the run game heavily if they can come out to an early lead, the team may also give Taliaferro more than a handful of carries if Forsett continues to struggle against the Steelers stout run defense.