The infinite murkiness of the Atlantic Yards financial projections

From Gothamist, 10/11/18, Hudson Yards Has $4.5 Billion In Taxpayer Money. Will We Ever See It Again?:

"Whether large-scale projects like Hudson Yards or Atlantic Yards pay for themselves is difficult to assess," concludes Doug Turetsky, chief of staff for the IBO [Independent Budget Office], which has conducted several studies of aspects of Hudson Yards financing but has never dared to attempt calculating a total public cost figure.

Well, it's true that the IBO's pre-project Atlantic Yards calculations were based on assumptions that have not panned out, like a steady buildout. Also, the developer's projections, both for themselves and for the public, were also based on unrealistic assumptions.

Also worth considering is what development would've happened anyway, without Atlantic Yards/Pacific Park, or whether a different, more realistic project might have delivered more (and faster) public benefit, as well as more certain private benefit.