One of the factors is also sharing.
Out here, many restaurants have embraced sliders as a means of selling the same amount of meat, but, in smaller, more easily shared portions. There are a lot of folks that will pass on a larger sandwich for dietary or appearance reasons, but, will eat a slider readily. Price points to entry are every bit as valid as total price of each sale. In truth if you are charging $2.75 for a single slider, that is 1/2 of a large $5 sandwich, and you are using exactly the same food costs, you are better off selling sliders. That is the math out here.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."