When we do pulling movements we should be thinking about retraction and depression of the scapulae (shoulder blades). Many athletes perform pulling movements incorrectly, compensating with humeral hyperextension. In humeral hyperextension the humerus moves behind the torso with no action coming from the retraction of the shoulder blades.
As athletes pull only with the arms the scapula goes into anterior tilt, and loses all stability. Essentially, none of the scapular stabilizers are doing their job. Not only that but when the scaps move into anterior tilt we contract the pec minor instead of actually training the back. Putting the humerus into hyperextension isn't a good place for it. It is extremely stressful on the anterior capsule putting athletes at risk.
This is my best attempt at humeral hyperextension when pulling, instead of true scapular retraction and depression. The following video is a better look at how the pull should be done. Notice that the arms don't move behind the toso. It's the scap performing a large majority of the movement with retraction.
Teach athletes to retract and depress the scaps first then pull with the arms. Sometimes it may make more sense to athletes when you break the movements up into parts. We actually use 2 part movements at various times throughout the year with baseball. Before we begin regular pullups we learn the scap pullup. After scap pullups we move to our 2 part pullups. From there we implement a full pullup. Using this progression helps our athletes to integrate their scaps into the movement, and stop shortchanging themselves.
To really activate the backside musculature like the middle and lower trap I like to have athletes visualize squeezing the scaps down and back throughout the entire movement. I've found cueing athletes to get a big chest helps in this department.