I just checked

http://www.wachtell.com (V1) and Chicago has 16 people there and NYU has 30. From a brief look at the site I couldn't tell, but do they have offices outside of NY? It didn't look like they did, at least a couple of the Chicago people were NY licensed.

http://www.sullivancromwell.(V2) com shows 21 from Chicago and 67 from NYU. All of the Chicago grads are NY except 4 overseas and one in palo alto. For NYU 12 of them are non-NY offices, 1 palo alto, one DC, and 10 overseas.

http://www.skadden.com shows 23 Chicago and 91 NYU at the NY office.

http://www.cravath.com(V4) shows 13 Chicago and a whopping 66 NYU, all with NY area codes.

http://www.davispolk.com (V5) shows 8 Chicago and 85 NYU at their NY Office.

All-in all, that is 81 Chicago and 339 NYU. That would seem to be in NYU's favor even if NYU is twice as large. On the other hand, if less than 30% of Chicago grads (60 per year about) are even interviewing for NY firms and about 80% of NYU's 450 grads (390) are shooting for NY, then Chicago's v5 NY Office placement is pretty impressive. Chicago's ratio would be 81/60, which is about 1.33, and NYU's ratio would be 339/390, which is about .85. That is a pretty huge difference in placement power.

edited for numbers.