It might just be me, but there seems to be some confusion as to what the move Drag Down actually is. It is usually connected to the Chinese term Tsai, and is considered one of the eight basic moves ( or Eight Gates).
But Drag Down is a poor translation of Tsai. First off, Drag Down implies a direction, as if the only way to Tsai is downwards. But that is not the case! You can find Tsai in many other places, in different directions. For example, in Single Whip, there is a Tsai to the side (made with the hand in the Crane Beak position, when the upper body turns to the right).
Tsai can also be translated as Pluck, a short, sharp jerking motion that can be done in any direction.
From now on, I will use Drag Down to describe the move which is found in the 13 Postures: the shifting of the weight, the rising knee, the push with the Tiger’s Mouth. The basic move Tsai will be associated with the idea of Pluck.