When most goalies are looking at a new stick, they usually get into their stance as they hold it to make sure the paddle height is correct. That is only part of the equation…
For proper size, they should also drop to their knees in a butterfly position (you’re in a hockey store… everyone will be somewhat familiar with what you are doing) to see how high the paddle length causes the blocker hand to be positioned.
If the paddle is too high, there will be too little coverage between your body and blocker hand meaning a large hole exists.
For too short of paddle lengths, the blocker will sit too low and goalies will be vulnerable to shots heading between middle of the torso to shoulder height.
If the paddle height is just right, the blocker hand will automatically drop into the optimal position so there is no hole between the arm and body.
Also, it is vital to understand each stick manufacturer measures paddle length differently so do not switch stick manufacturers without getting into the stance and butterfly to make sure the paddle length matches your expectations.
Below I have included commentary and pictures from Finnish goalie-guru Jukka Ropponen to help you visualize this better.
This photoset demonstrates how important it is for the modern goalies also consider their position in the butterfly when choosing their stick and not just go by what feels good at the stance – after all, most saves today are made down from the ice.
Tall stick pushes the stance up a bit, but this one is still OK
Now you really see the difference when goalie goes down to butterfly and too tall paddle pushes the blocker arm up leaving a nasty hole between the body and the blocker arm.
Proper size stick works well also when goalie plays down on the ice in butterfly position. See how the goalie can still keep the blade on the ice and keep blocker arm at right position next to his body.