It happens every season, but none of us are ever prepared for it. When a quarterback of a top offense gets injured, the fantasy football impact spreads far beyond the owners of that player. In fact, it can affect the entire offense of that team, drastically altering the value of the backs and receivers playing with the new signal-caller.

In just the past few weeks, we’ve seen Matt Cassel of Kansas City and Jay Cutler of Chicago suffer injuries that will likely keep them out for the rest of the regular season. (Cassel has already been placed on injured reserve, while Cutler might have shot at coming back for the playoffs, at best.) In Houston, the situation has become increasingly dire, with Matt Schaub and his backup Matt Leinart lost for the season in consecutive games.

Suddenly, guys like Tyler Palko, Caleb Hanie and T.J. Yates are in control of offenses featuring many key fantasy performers, guys who are on teams headed for the fantasy postseason in many cases. It’s always hard to gauge just what kind of effect the injuries will have.

There’s no hard and fast rule. Your best bet is to take it on a situation-for-situation basis.

Kansas City was already a pretty rough stretch for fantasy owners anyway. The early-season loss of Jamaal Charles left the Kanas City Chiefs with a revolving door at the running back position, while their promising tight end Tony Moeaki never made it out of the preseason. As a result, the onus was on Cassel, and his sporadic production weighed down Dwayne Bowe, who was coming off a monster 2010.

With Palko in there, it’s hard to imagine any Chiefs being viable fantasy options the rest of the way. Bowe still managed decent stats even as Palko flamed out the other night against the Steelers, so he deserves WR3 consideration. Otherwise, if you’ve got some Chiefs stashed in the bowels of your roster, abandon hope.

The Bears didn’t scale things back too much with Hanie under center against the Raiders. His numbers were actually pretty fine if you overlook the three interceptions. It was assumed that Mike Martz might lean heavily on Matt Forte, but Martz, ever the contrarian, split Forte’s carries nearly right down the middle with the resurgent Marion Barber, resulting in one of Forte’s least-productive games all year.

On the other hand, Johnny Knox, who was a forgotten man after showing breakout potential in 2010, came up with big numbers with Hanie under center. I wouldn’t count on Knox being consistent the rest of the way. The Bears seem to have a different top receiver every week. One guy who probably should be out of consideration is Earl Bennett, who seems to have a rapport with Cutler, but caught just one pass from Hanie last week.

As for Forte, I’d be a little concerned as an owner. He’s already got Barber vulturing touchdowns. If this becomes a true committee approach he’ll have a hard time matching what he’s done so far this season.

The Houston situation is the hardest one to read, simply because there are so many unknowns. For one thing, it’s hard to imagine the Texans sticking with Yates, especially considering their playoff aspirations. Then again, how much better would Jake Delhomme (already elevated to the backup going into Sunday's game against the Atlanta Falcons) do coming off the street?

Obviously, you can’t bench Arian Foster. He’s good enough to run by stacked defenses and catch outlet passes out of the backfield to find a way to score. I also still like Ben Tate as a flex play. The worrisome guy here is Andre Johnson. Maybe the two catches he got last week were a result of rust from not playing for more than six weeks.

If, however, the poor stats are a symptom of the troubled quarterback situation, there is no guarantee that things will get better. I own Johnson in one league and am considering doing the unthinkable. I’ve got some decent alternatives, and I can’t abide little to no production from a starter as the playoffs approach.

Yes, I may have to bench Andre Johnson. That’s the kind of havoc injured quarterbacks can cause to a fantasy football season.