It seems to me the answer should be very straightforward.
All they have to do is determine whether there are any New Balance athletes who don't have reductions. If there are, then reductions aren't standard in New Balance contracts.
If all of New Balance's clients have reductions in their long-form contracts (are there two types of contract?) and not in their short-form contracts, then you'd have to give the benefit of the doubt to Nike.
Seems simple enough to me, no?
LOL ... sure, Nike would love to get a hold of ALL the NB contracts for their review. This will happen when Nike yields all of their contracts to NB for NB's review. In others words, it will never happen.