Renovated Yankee Stadium could also have been eligible for landmark status in 2006 as a 30 year old New York City building. They conveniently denied the status a year before it's eligibility.
I heard rumors that the parking garage near the bat may be demolished. If this is the case then the land that the parking lot occupies could have been used as replacement parkland.
Also Saving Gate 2 was not going to impede on any replacement parkland.