We see a lot of posts of good Hand Eye around the net with deflections and pucks knocked into the net but what a lot of players don't realize is they can use their hand eye in a defensive manner as well. A good stick means you are taking away passing lanes and players must look at other options or try to get the puck through you.  Some players will try to saucer pass the puck over your stick to an opponent.  If you are able to knock the puck down, you can create a turnover and attac the other way. 

In this clip, the puck is knocked down at the blue line and turned the other way quickly. 

One thing to note is that the Toronto player does not adjust his hands (sliding his top hand down) but reacts and knocks the puck off the pass.  

Work on your hand eye and make sure that no puck gets past you in the defensive zone.