Losing a franchise quarterback for any amount of time is going to be a big blow, but with how well Ben Roethlisberger has been playing so far, he might be as close to irreplaceable as a player can get in the NFL right now. And, when the player replacing him is Michael Vick, well... the Steelers might be in some trouble for the next few weeks.

Based on a four-week timetable for his return from a sprained knee, the Steelers are going to lose out on a lot with Roethlisberger's injury. Our Sportsline projections have the Steelers' odds of making the playoffs dropping from 51.8 percent to 34.7 with Vick starting four games in Roethlisberger's place, with an average drop of 5.0 points per game for the offense. That will obviously have big Fantasy repercussions, as you can see here from the rest of the projections:

Sportsline projections
Roethlisberger 20.8 6 96 143 67.10% 1192 6.9 2.9 12
Vick 16.7 16 82 134 61.20% 973 4.8 3.3 53
DIFFERENCE -4.1 10 -14 -9 -5.90% -219 -2.1 0.4 41

Vick's ability to run the ball helps boost his Fantasy appeal a bit, though our projection system isn't terribly high on him in that regard; he is projected for just 53 rushing yards in four games. However, the Steelers have enough weapons around Vick that he might still be able to remain Fantasy relevant, as his No. 16 ranking at the position illustrates. Antonio Brown can make any quarterback look better, and Le'Veon Bell is the best check-down option in the league. The return of Martavis Bryant also helps in this regard, and Vick is ultimately projected for 16.7 Fantasy points per game.

If you're looking to replace Roethlisberger, Vick probably shouldn't be your first choice. With Derek Carr looking much improved and surrounded by real weapons in his second season, he would be my top target at 37-percent owned. However, if you need a bye-week replacement or No. 2 quarterback, Vick might be worth a roll of the dice.

Sportsline projections
w/ Roethlisberger 14.7 2 31 435 14 2.6
w/ Vick 11.9 3 28 366 13.1 1.9
DIFFERENCE -2.8 1 -3 -69 -1 -0.7

The drop in rank from No. 2 to 3 isn't huge, but 2.8 Fantasy points per game isn't an insignificant dropoff either. If you own Brown, you likely used a first round pick or something close to that to acquire him, so this injury could be particularly devastating. Vick threw the ball six times in Week 3, and only one of those passes went Brown's way; it fell incomplete. Brown is still one of the toughest covers in the league, and Vick has enough arm to hit him downfield when he gets behind the offense. Still, you have to imagine the Steelers will throw the ball significantly less often with Vick, and a large part of Brown's appeal was the huge pass volume. This injury hurts him more than anyone, though that doesn't mean you should be looking to bench him. He should still be a top-five wide receiver, but all of a sudden, there's downside to a guy who should be the safest receiver in the league.

Sportsline projections
w/ Roethlisberger 17.6 1 69 300 4.3 2.7 20 211 0.5
w/ Vick 14.8 2 65 264 4.1 2.1 18 178 0.4
DIFFERENCE -2.8 1 -4 -36 -0.3 -0.6 -2 -33 -0.1

If there is one player who might not lose out much with Vick under center, you would think it would be Bell. Running quarterbacks tend to open things up for their running backs, increasing their efficiency, and a stacked box means more potential for a big play if Bell can find his way into the second level. Our projections are conservative on Bell, but the bulk of his step back doesn't really come from a drop in per-touch production; he just isn't expected to find the end zone as much.

Given the expect dropoff in the offense overall, that isn't exactly a shock. Bell's replacement DeAngelo Williams was a touchdown machine in the two games Bell missed, and the offense he was playing in clearly had more of an impact on that than Williams' own abilities. Fewer opportunities to score will obviously harm Bell's value, but he does so much between the running and passing games that it's hardly time to panic. If Bell gets through the next four games and comes out on the other side averaging 14.8 Fantasy points per game, its hard to imagine his Fantasy owners would be anything but thrilled.

The rest of the Pittsburgh offense obviously suffers significantly in this change, especially the fringe-y Fantasy types. After a terrific opening game, Heath Miller has just two receptions in each of his last two games, and is probably on the outside looking in for Fantasy relevance; he is projected to fall to 20th among tight ends at 4.3 Fantasy points per game with Vick under center.

Martavis Bryant might be the biggest loser of all, because he has true star potential as the deep threat for Roethlisberger. Roethlisberger has been one of the best deep ball passers in the league over the last couple of seasons, and he's made Darrius Heyward-Bey into someone to keep an eye on in Bryant's absence; based on what Bryant did as a rookie, he should have even more upside than that. Now, after a four-game suspension and in the wake of Roethlisberger's injury, we might be waiting until Week 8 before Bryant hits his full potential. That's a long time to wait, especially for someone you might not have known was suspended when you drafted him.

The Steelers are going to miss Roethlisberger, and Fantasy players might miss him even more.