" top NYC CPA " -- oxymoron?  Reminds me of the one who overlooked a five-figure Section 199A deduction for several years before the 2018 law change.  

If the tenant were filing the form, it would show the gross rents.  Is the management company the agent of the tenant?  In most places, they are the agent of the landlord, but New York does things differently. In the real world, real estate agents aren't always used in residential rental leases, but apparently in New York it's considered a necessary expense.

The Regulations to Section 6041 tell us: 

(f) Amount to be reported when fees, expenses or commissions are deducted -

(1) In general. The amount to be reported as paid to a payee is the amount includible in the gross income of the payee (which in many cases will be the gross amount of the payment or payments before fees, commissions, expenses, or other amounts owed by the payee to another person have been deducted), whether the payment is made jointly or separately to the payee and another person. The Commissioner may, by guidance published in the Internal Revenue Bulletin, illustrate the circumstances under which the gross amount or less than the gross amount may be reported.

--so maybe there is some guidiance from IRS on reporting less than the gross amount.  Ask a top NYC CPA about it.