This skill will be used mainly by zergs to pull enemy players, then kill them before they have any chance to react. They already use dark convergence to pull players before ultidumping them. When I get hunted by a Zerg and tried to escape into a keep I regulary got stunned or pulled back when I was already at the door. Giving Silver Leash a buff will even increase this.
They already use dark convergence to pull players before ultidumping them.
This is actually a valid reason to either remove that effect from DC or give it to all pullchain skills.
It doesn't make sense that set gives AoE pull with 1s stun when single-target skill doesn't stun.
Probably removing stun from DC would be more balanced, tho. Technically, pull already stuns you for the flight duration - which happens in teamfights. 2s of stuns would be too much.