Hitboxes and Hurtboxes
Yeah, that isn't Vayne having a huge hitbox, it is Thresh's death sentence having a huge hitbox.
This was a quote from a thread I was in that claimed that Thresh's hitbox was too big.
I quickly screenshotted (if that's a word) a video where Thresh's hitbox "should have missed". It was a frame right when the hook connects. Then added in what I believe the hitboxes to be
http://i.imgur.com/9am7pRd.png
Red is Thresh's hitbox on his hook (which I was actually quite conservative with) Yellow is (approximately) Vayne's hitbox
The area at which they meet is when they will hit. As you can see, they overlap (even by a bit). The "Snapping" effect, is nothing more than visual confirmation that it connected (and so Thresh's "drag" animation makes sense. You want to be dragging the opponent, not half of the opponent's body and other half of it is air) Thresh's hook is made so that the hook wraps around the CENTER of the champion before moving them.
Am I saying that Thresh is balanced? No Am I saying that the hitbox is over the top? Eh, maybe. Am I saying that Pre-Rework Nidalee's Spear Throw was balanced? Hell, no.