Smooth vs. Chunky vs. Broken Squiggles
Pyth, 25 bytes

mcl@.:d2.:z2tlzc2"\__//\/


Test suite

Outputs smoothness, chunkiness. Basically, it takes the hard coded string and cuts it in half. Each half is decomposed into its 2 character substrings, and the same is done for the input. We take the intersection, resulting in the south and chunky pairs. Then, we take the the length, divide by the number of pairs, and print.