If you want to know why more than 450 city park workers are about to be laid off or why the Parks Department has imposed outrageous fee increases, just take a look at the new Mets and Yankees ballparks (above).
This is not something City Hall wants you to know. Parks officials only confirmed the revenue loss after the Daily News asked why budget documents showed a dramatic drop in the agency's franchise income since 2008.
At first glance, that would seem impossible.
Everyone knows private money-making operations have exploded in our parks under Bloomberg. Fancy new restaurants, food kiosks, green grocers, bike rental and private sporting concessions - you name it.
So how could total income from all this business activity be falling?
Well, it turns out that Shea and the old Yankee Stadium - both of which sat on park land, and were owned by the city - were the Parks Department's biggest revenue generators.
Under the old Yankee Stadium deal, the city was assured a percentage of gate receipts, a percentage of food sales, even a percentage of the team's cable revenue.
Because of that, the old stadium produced as much as $15 million a year for Parks - even after deducting costs for stadium upkeep.
Likewise, the Shea Stadium deal generated as much as $9 million annually for the city.
As recently as 2008, the two ballparks represented nearly half of the $51 million in concessions revenue generated by the entire Parks system.
On top of that, the city was taking in an additional $6 million annually from parking fees at Shea and the old Yankee Stadium.
Once the new ballparks opened, all that revenue disappeared - even the parking money.
Today, the Mets keep all their parking revenue. Meanwhile, the Yankee Stadium garages, run by an independent firm, are nearly bankrupt and may never produce the $3 million annually they agreed to provide the city.
This loss of $30 million each and every year is a hidden cost to taxpayers from the new ballparks.
Parks officials insist there's no real problem.
"The loss of revenue from Yankee and Shea Stadiums has no direct impact on the Parks Department's budget as the revenue was directed to the city's general fund and does not affect the agency's operations," spokesman Phil Abramson said.
That is pure nonsense. Bloomberg's planned budget reductions for the Parks Department this year specifically said that any increase in fees to the public would help prevent layoffs and other drastic cuts.
The result was a doubling of fees for tennis permits - from $100 to $200. Adult memberships to recreation centers went from $50 to $100, and from $75 to $150 if the center has a pool.
Even fees for adult leagues to use ballfields increased by 60%.
In other words, the Mets and Yankees save millions and the rest of us make it up with huge fee hikes.