[UPDATE: At 12:30 Wednesday, Manning was officially ruled out for Sunday's opener against the Texans by general manager Bill Polian.]

Let the national freak out begin. Peyton Manning is not likely to play this week unless he has a miraculous turnaround from the effects of his neck surgery. The speculation is growing that he will miss multiple games. A few weeks ago, the line for the Colts opener at division rival Houston was close to a pick em, with the Colts a 1 point favorite in many places.

With yesterday’s news, and the likelihood that 39-year old Kerry Collins will start for Indianapolis, the line has swung to the Texans favored by 8.5 points to 9 points, almost a 10 point swing. Now, that line was already moving before the news about Manning (though we’ve known for a month that he was not participating in preseason, and that likely was already having some impact). Is Peyton Manning really worth 10 points per game? And how much of a win total drop should we expect for the Colts if Manning misses time?

I ran a quick twitter poll, where I asked people to assume the Colts were a 10-11 win team with a healthy 16 games from Manning, and then project a 16 game win total without. The average response was 5.6 wins, with a range from 3 to 8 wins. Let’s see how that nearly 5 win drop matches up with historical data.

To try to look at this question, I went back and looked at every Hall of Fame quarterback since 1978 who missed at least 2 starts in a season. I then added a couple of qualifiers. I limited it to ages 27-37, and I excluded any seasons that were the final two seasons as a starter (to avoid any decline phase). I also excluded any season where another Hall of Famer was the backup (Steve Young and Joe Montana in 1988 and 1989).

The goal here is to at least get a list of comparable players to Peyton Manning, so we can then mentally adjust for the Colts’ situation from a reasonable baseline. A few years ago, Doug Drinen of pro-football-reference did a study on what a starting quarterback was worth. The answer was about 2.3 points a game and 1 win over the course of a 16 game season. Now, that was an average starting quarterback, not a Hall of Famer, and Doug went on to estimate (before Brady’s injury that season) that the Patriots would be a solid 10 or 11 win team if Brady were hurt all year and an unknown backup was pressed into duty. A few weeks later, Brady did get hurt, and everyone was freaking out about the Patriots’ collapse without the irreplaceable Tom Brady, which prompted this response. Consider this my “reports of the Colts demise are greatly exaggerated” pre-emptive strike. (and yes, I did write this, so I wasn’t expecting the Colts to win 12 or 13 games anyway).

So anyway, back to our Hall of Famers and their backups. My list includes 3 seasons each of Steve Young, Troy Aikman, Dan Fouts, Warren Moon, Dan Marino, and Jim Kelly; 2 seasons of John Elway; and a season each from Joe Montana, Terry Bradshaw, and Bob Griese (lest you complain about these last two, they don’t hurt the numbers, and the difference between Bradshaw and a young Mark Malone were among the largest dropoffs). I then looked at the average points for and against both with the Hall of Famer starting and without, as well as wins and losses.

When the Hall of Famers started, their teams averaged 24.0 points, 19.5 points against (+4.5 point difference per game) and won 61.5% of their games, which would equate to 9.8 wins.

When their backups started, those teams averaged 22.3 points, 21.4 points against (+0.9 point difference per game) and won 45.1% of the games, which would equate to 7.2 wins.

The differences between the Hall of Famers and the backups was a +3.6 point differential per game, and 2.6 wins prorated over 16 games.

Now, that 2.6 wins could be the difference between a playoff appearance and not for a team like the Colts. Let’s talk about some adjustments. The backups, since I excluded two seasons of Steve Young, would not be any better than a 39 year old Kerry Collins, and arguably worse on average. The most accomplished as starters after their relief role were either Scott Mitchell or Elvis Grbac or Don Strock. The rest were either career backups or former starters at the end of their careers. I don’t see any reason to downgrade that projection based on Collins compared to the typical backup.

As for Manning, yes, I think he’s an above average Hall of Famer and one of the best at his position of all-time. I think he’s a little more important than even the typical Hall of Famer, even though he is a little older than the average Hall of Famer I used for this study. Even if we bump him up, though, over the average dropoff between Hall of Famer and backup, we can’t get crazy with it. There’s no way he’s worth more than double the composite average of every other Hall of Famer versus his backup.

So I think if you want to assume the Colts were a 10.5 win team with a completely healthy Manning (the 9.5 to 10 win Vegas totals necessarily had a slight chance of Manning missing games already built into the line, so that’s reasonable), then I think the average projection for this roster should be about 7.5 wins. That should be enough to swing them from the favorite to win the AFC South to an underdog, but still a viable playoff contender if things break right in the AFC South.

Collins still has a well above average receiving group to throw to, with Reggie Wayne, Dallas Clark, Austin Collie and Pierre Garcon. The defense still has Freeney and Mathis. If this team is significantly worse than 7 wins, it will be because other things–Wayne and Clark declining, Freeney or Mathis getting hurt–caused them to fall further.

Now, I think it’s unlikely that Manning would miss all season, so I think the Colts win projection should be somewhere between 7.5 and 10.0 wins, depending on how many games you think he misses. Here are my predictions for the Colts while/if Manning is out:

  • The Colts will not be nearly as bad as people think, as we tend to overestimate the value of the elite quarterback (flashback to the line for New England/Green Bay jumping 9.5 points when Rodgers was ruled out with a concussion, when I said the Packers would keep it close)
  • Kerry Collins will put up near league average passing numbers. I don’t think he is what he was, obviously, at age 39. What he has been, for all of his career, is a guy that avoids sacks and gets rid of the ball quickly (not Manning quick, but way better than a typical QB, which is why he is a good fit here). When you factor that in, he has been a league average passer, throwing to inferior receivers compared to the Colts, but behind a better offensive line.
  • I will be taking the Colts +8.5 on Sunday, though I expect that line to move even more as the public panics.

[photo via Getty]