When Chicago Bears third-stringer Kyle Orton took his first snap in Monday night's game against the Minnesota Vikings, he became the 60th different starting quarterback in the league this season, the most since 1999.
Orton, who started his first game since his 2005 rookie campaign, was the fourth quarterback to make his first start of the season this week, joining Todd Collins of Washington, Shaun Hill of San Francisco and Carolina's Matt Moore. The Week 15 juggling continued a season in which the quarterback carousel has spun wildly out of control.
"There aren't many teams this year who have had the luxury of lining up with the same guy every week," said Carolina coach John Fox, whose Panthers are the only franchise in the league to have employed four different starters in 2007. "It's just been one of those years where it seems like every week there has been a lot of change."
Last season, NFL teams used only 50 different starting quarterbacks, the fewest since 2001. Since 1999, which marked the second year in a row with 62 starters, the average has been 55.0 starters.
It isn't only the large number of starters, however, but also the changes made overall that have reflected the instability and lack of continuity at the game's most critical position this year.
In the 14 weeks since the opening weekend of the season, there have now been 64 quarterback switches, an incredibly high average of 4.6 per week. For all of 2006, there were only 26 switches. There hasn't been a single week yet this year in which every team in the league returned its starting quarterback from the previous weekend. And in six different weekends this season, there have been five or more changes at starting quarterback.
For Week 11, there were 10 changes, the most in any weekend in at least the past seasons. There have also been weeks of nine (Week 9) and eight (Week 15) changes, the second- and third-most, respectively, in the past seven years.
Only 12 teams in 2007 have started the same quarterback every week. Seven teams have employed three starters or more. Last season, half of the league's 32 teams used the same starter for all 16 games and only two clubs, Miami and Tampa Bay, used three starters.
Not all of the changes this season have been a result of attrition. There have been 18 quarterback switches this season that were coaching decisions, not based on injury but on performance. By comparison, there were only seven changes in 2006 in which the switch was made for non-injury purposes.
Len Pasquarelli is a senior NFL writer for ESPN.com.