Strong ties to Boston with the founders of TC. Brad Feld went to MIT and still has a strong and love for the area. David Cohen sold one of his startups there.

Because YC is supply-constrained. If you believe there are more fundable opportunities than YC can handle then it makes perfect sense to "compete" in Boston.

I wouldn't be surprised if it were all just a story, though.

pg commented above, so that can't be their reason. Maybe they just like Boston?

Because there's a gap in Boston that needs filling? A lot of start-ups want to go to Boston, or can't make it to California.

Yeah but according to them, they were planning to go to Boston when YC was already filling that gap.

So if you wanted to fill a gap, why not go somewhere that doesn't have an incubator program in the first place?

Because Boston's an incredibly dense city? I dunno, I'm just guessing.

As someone else mentioned, both David Cohen and Brad Feld have a history in Boston, it's where they got their start (as it has been for many others thanks to MIT and Harvard). There was also a strong push for quite a while from the Boston and Cambridge entrepreneurial community.

Is there any competition at all in NYC?