It is more likely that he'll pull a Pirlo than a Lampard.
Like Pirlo, he'll get outdone by the physicality of it all and his age will show. MLS doesn't lack athletes, plus given how back and forth games are over there you'd think it'd be even more difficult!
Don't forget with Lampard that he was always an incredible athlete. He still had more than to offer playing for us before he hit the States. He wasn't just going to lose it.
Though at the same time if I were an NYCFC supporter I wouldn't be too dismissive. He might struggle to keep up at times but if you can find a way to manage his stamina he's still an incredible player: Still has the physicality, still amazing technically and still amazing at controlling play in the middle, still has an incredible passing range, and so on and so forth.
Then you think about how much of a boost it'll be to their players to be able to work with a guy like Yaya.
I think that especially given the fact that he'd be a DP on a very high pay that the stamina issue is too big to be ignored. Unless NYCFC can somehow be assured that the MLS (and the relatively easy fixture schedule) won't be too much for him, but I doubt that'll be the case.