From Dave Tuley's sports-betting feature in the Daily Racing Form (registration required):

"During football season, a lot of discussion goes on in the sports books about how much a player is worth to the point spread. Just like in baseball where the starting pitcher has the most impact on the odds, the starting quarterback carries the most weight in football handicapping. If the first-string quarterback is injured, you have to determine not only how good he is but also the depth of the dropoff to the backup. In some cases the line might move a touchdown or more while in other cases it might just be a few points.

"Brett Favre started 275 consecutive games for the Green Bay Packers and was rarely even considered "questionable" on the league's injury reports. He retired this week, and now we know how much he was worth in future-book odds.

"On Monday afternoon, the Hilton had the Packers at 14-1 to win the Super Bowl. After the team announced his retirement on Tuesday morning, the Hilton [adjusted] the odds to 25-1 on the assumption that relatively untested four-year backup Aaron Rodgers will take over the starting job."