The NFL is a very dangerous place for quarterbacks. Unless you are like Brett Favre in his prime, you are going to get hurt at some point, and your team will have to play without you. For some teams a hurt starter isn’t that big of a deal.

A competent backup can take over and keep things on track – or improve them as we saw with Colin Kaepernick and San Francisco last year. When the backup is not particularly adequate, though, teams can really struggle without their starter.

For handicappers, a big gap between a starting quarterback and his replacement can lead to massive uncertainty. You bet based on what you expect to see on the field. However, since you can’t anticipate injuries, you could find your money on a team that is very suddenly much different than what you thought you were investing in. Here are four teams heading into this NFL season with a very large gap between the quality of their starting quarterback and that of their primary backup:

Aaron Rodgers and B.J. Coleman, Green Bay Packers

It’s hard for a team to have any more faith in a starter than the Packers have exhibited. They cut Graham Harrell, last year’s backup, during the preseason after he had had a poor outing. It seemed clear, then, that Vince Young had miraculously risen from the ashes to earn the backup job. But then he got cut at the end of the preseason. Now seventh-round pick B.J. Coleman out of football powerhouse Tennessee-Chattanooga is the presumed backup. The drop off between Rodgers and Young would likely have been as big as any in the league. The drop off between Rodgers and Coleman is so massive that it’s just plain irresponsible on the part of the Packers. Maybe the team is spoiled by the durability of Rodgers and Favre before him, but this just doesn’t make any sense at all. A real contender is just one hit away from doom. UPDATE: On Monday the Packers cut Coleman. As of now Rodgers is the only QB they have. Obviously they will pick someone up -- reportedly Seneca Wallace -- but he won’t be ready. This is the most bizarre situation I can remember.

Peyton Manning and Brock Osweiler, Denver Broncos

This one is almost as confounding as the Packers – and just as irresponsible. I understand that Manning is one of the great quarterbacks of all time, and that if he is healthy he will almost certainly play all the snaps that matter. That makes it hard to get a great backup to sign up. Manning is also 37 years old, though, and just one season removed from a neck injury so serious that it cost him an entire year and put his entire career in jeopardy. And he looked more than a little mortal in the playoffs last year. While it’s absolutely possible that Manning will shine and have another great season, it’s also possible that any hit could cost him a game, a month, or the rest of the year. Any QB is vulnerable on any play – never mind one like Manning. To have a guy like Brock Osweiler behind Manning, then, is just plain ridiculous. Nothing against Osweiler – I liked him in college, and think he could be serviceable with time. He has 12 career passing yards, though, and is absolutely not in any position to take over a Super Bowl favorite and keep it on track. The Broncos have gone all in on Manning, and that just doesn’t make any sense.

Matt Ryan and Dominique Davis, Atlanta Falcons

I guess the positive is that Davis is used to being a backup for Ryan – he sat on the bench while Ryan excelled for Boston College in 2007. After that, Davis had one mildly-successful season as a part time starter at Boston College, played a year in community college after failing out of BC, then had two strong years against weak competition at East Carolina before going undrafted in the NFL. Davis can throw – he went an entire game against Navy without throwing an incompletion while at East Carolina. He has not thrown a regular season pass in the NFL. He did gain a lot of hype last year with a strong preseason showing, but given an added opportunity to shine this year in the preseason he was largely underwhelming. Playing significant time in all four preseason games, he completed just 52.6 percent of passes for two touchdowns and three interceptions. That was not against top competition, either, so it is hard to imagine that he is ready for primetime. The Falcons insist they are finally going to take the step forward and shift from promising to dangerous. I have doubts about whether that will happen with Ryan at the helm, but it certainly won’t if he goes down.

Ben Roethlisberger and Bruce Gradkowski, Pittsburgh Steelers

I feel like the Pittsburgh Steelers are like a gaping wound this year, and Big Ben is the bandage trying hard to keep things together. If he were to fail in that task – and we know he isn’t the healthiest of quarterbacks – then this team could be in serious trouble. It wouldn’t just be the fall off in play - though Gradkowski at this point in his career would be a big step down from Roethlisberger. It would be the mental damage the loss of Roethlisberger would be to what seems from the outside like a very fragile team. It would be very easy for this team to be a step slower and hit not quite as hard with the backup in place – just like so many NHL teams don’t play quite as hard in front of a backup goalie. I don’t think that Gradkowski is among the worst of the backups by any means, but he is not what this team needs at this point, and if he were forced to start it would be an easy decision to bet against the Steelers.

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