Apparently, a lot of sports writers are privy to numerous details about Russell's contract -- when he was paid how much, which parts were guaranteed, etc. -- but nobody can quote from it. It was apparently modified in 2009, but nobody can quote from the modification, either. I'm not sure if the Raiders' grievance sets forth their position (as opposed to consisting merely of a prayer for relief), but nobody is quoting that, either.
Russell's agents are saying that any money paid for 2010-2012 was fully guaranteed, and is thus not recoverable. That sure makes a lot of sense. It would be weird for the Raiders to give Russell an advance on non-guaranteed salary. Also, from piecing together
what some sports writers are saying, the money was apparently in the form of a bonus originally, but was transmuted into a salary advance by virtue of the 2009 modification (something to do with salary cap implications). To go from guaranteed money to non-guaranteed money, though, there needs to be consideration (e.g., the amount of money would have to increase); otherwise the modification is unenforceable.
Until someone quotes the contract, or until the Raiders at least tell us what their theory is, we're all somewhat in the dark. But I'm having trouble coming up with a realistic scenario under which the Raiders would have already paid out non-guaranteed money for the 2010 regular season or beyond.