Goblins are crafty creatures and their movement patterns often confuse novice smitemasters. One useful thing to remember is that they hate your sword and will try to stay away from it. They will only move to a tile adjacent to your sword if they have no other choice.
To help visualise the last point, all the images on this page use alternate floor texture that shows all the tiles adjacent to the player's sword, like so:
Note how this goblin doesn't step near your sword while also trying to get as close to you as possible.
No matter how many goblins there are, they still won't step near your sword.
In a 4 tile wide corridor, defending your position against multiple goblins is much harder, you will likely have retreat a few times. 5 tile wide corridors might as well be considered open spaces when dealing with multiple goblins.