From the article linked to above:
The CBA extension negotiated in March, 2006, came after the start of the league year was pushed back twice. The CBA was set to expire after the 2006 season, but owners wanted to avoid entering an uncapped year, which would have been the case in 2006.
The sea change in the agreement was that rather than having the players share in only designated gross revenues (DGR), which were essentially television money and ticket sales, now all revenue, national and local, was to be included. Also included in this agreement was a mechanism for the owners to receive cost credits; money that would be taken off the top of all revenue before the remainder was shared with the players on a 59.6-percent basis to cover salary and benefits. In 2008 and 2009, the last two years of a salary cap, those cost credits totaled slightly more than $1 billion.
The new deal had a term of seven years. However, because the owners would have to subsequently agree to a supplemental revenue sharing plan where high-revenue teams would pay out money to lower-revenue teams, the owners had included in the CBA an option for either side to opt out of the final two years (2011 and 2012) by November, 2008.
So anxious were the owners to opt out, they notified the NFLPA of their intention in May, 2008, after just two years of the new terms. At that time, as has become clear, they also began plans for a lockout, renegotiating contracts with their broadcast partners, and pressuring them to include language that would pay the owners their entire $4.4 billion of TV money in 2011 even if no games were played. They also hired Bob Batterman, who had counseled the National Hockey League during its lockout of the players...
...Consistently, the league claimed costs had outpaced revenue. At a league meeting last March in Orlando, Carolina Panthers owner Jerry Richardson told his fellow owners that we have "to take back our league."
At the same time, commissioner Roger Goodell consistently championed for an 18-game regular-season schedule, despite the physical toll the current schedule takes on its players.
But, the bottom line was still money. The NFL's goal in taking back their league was to want another $1 billion taken off the top of the revenue before the rest would be shared with the players. The NFL asked for that in mid-2009. The NFLPA's response then, and ever since, was "Why?"
To agree to such a large reduction, which would have led to each team saving, on average, $18.6 million, the NFLPA quickly said, "Show us the books."
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