The rest of the story is subscription-only, but yesterday Forest City Ratner spokesman Joe DePlasco claimed that the agreement includes "the arena, team and hospitality assets."
Maybe it hasn't been cut in half, but there's no reason to think it adds up to $20 million a year. In other words, they may be saying that recent reports are imprecise, but they're changing the subject by not answering the more important question: what the deal is worth.
According to the Barclays Center Project Preliminary Official Statement prepared by Goldman Sachs, a chart (p. 95 of the PDF) summarizes the allocation of certain revenues expected to be generated from the Arena Project between ArenaCo and New Jersey Basketball pursuant to various agreement.
As seen above, under ArenaCo, it allocates $10,000,000 annually in Naming Rights Fees.
Under New Jersey Basketball, it allocates only "Certain fees under Naming Rights Agreement."
If the latter sum were worth $10 million a year, wouldn't it be spelled out?