Approximately 25,000 Sunni insurgents from groups such as the 1920s Revolution Brigades, the Jaysh Mohammed, and the Islamic Army of Iraq have turned against al Qaeda at the behest of their tribal leaders.
Given that insurgent numbers were long given as 20,000 or so, has a declining insurgency really offered up more than they had at their peak?
Clearly not. This surely represents the shooters and supporters, so it probably represents 2,500 shooters plus people who represent the figurative "sea" in which the shooters swam.
And it explains why there is still fighting when more appear to have defected than existed in enemy ranks. Opponents of the war could easily charge fraud if they just cite numbers.
This is good news. But don't let the number confuse you--in either direction--about the significance.