It's not just the additional games - if the Yankees miss the playoffs, less fans will go to games the following year. And it would be significant.
I don't know who buys a Nunez jersey. I know a lot of people who bought a Cano, Sabathia, Tex, Granderson jersey/shirts, etc.
On a side note, I hate those Yankee jersey t-shirts with names on the back. The jerseys don't have names on the back. Why does your t-shirt?