There is a difference between the "close-set hocks" that the Draft folks admire...and cowhocks.
Close set hocks, is where the hind legs are straight, yet the pasturns and hocks are closer together than the norm. In cow hocks, the hocks alone are close together...and the pasturns are usually much further apart. This does not present a "straight" leg at all, and can cause interferance in the hind, if extreme.