All 3 of the defenses (Block, Dodge, and Parry) are affected by position, though not all on mobs:

Attacks from the rear cannot be parried. Mobs sometimes do so anyways - this can be due to a bug or because they turn very quickly in place.

-Wowpeida: Parry

Players can only dodge attacks if they are facing their opponent, however a mob can dodge attacks that are from behind.

-Wowpeida: Dodge

All creatures will now report a Block on attacks from the front, reducing damage caused instead of converting the attack into a "Miss." Creatures will no longer be able to Block attacks from behind.

-Wowpedia: Block

There may be other effects, this is the only one I could remember off the top of my head, and I don't play a rogue!

All 3 of the defenses (Block, Dodge, and Parry) are affected by position, though not all on mobs:

Attacks from the rear cannot be parried. Mobs sometimes do so anyways - this can be due to a bug or because they turn very quickly in place.

• Wowpedia: Parry

Players can only dodge attacks if they are facing their opponent, however a mob can dodge attacks that are from behind.

• Wowpedia: Dodge

All creatures will now report a Block on attacks from the front, reducing damage caused instead of converting the attack into a "Miss." Creatures will no longer be able to Block attacks from behind.

• Wowpedia: Block

There may be other effects, this is the only one I could remember off the top of my head, and I don't play a rogue!

Attacks from the rear cannot be parried. Mobs sometimes do so anyways - this can be due to a bug or because they turn very quickly in place. - Wowpeida: Parry

Couldn't explain it any better than Wowpedia. I thought at least one of the other defenses, Block or Dodge, was not possible against attacks from the rear, but I can't find confirmation of that. Still, removing one of the 3 is useful enough.

There may be other effects, this is the only one I could remember off the top of my head, and I don't play a rogue!

All 3 of the defenses (Block, Dodge, and Parry) are affected by position, though not all on mobs:

Attacks from the rear cannot be parried. Mobs sometimes do so anyways - this can be due to a bug or because they turn very quickly in place.

-Wowpeida: Parry

Players can only dodge attacks if they are facing their opponent, however a mob can dodge attacks that are from behind.

-Wowpeida: Dodge

All creatures will now report a Block on attacks from the front, reducing damage caused instead of converting the attack into a "Miss." Creatures will no longer be able to Block attacks from behind.

-Wowpedia: Block

There may be other effects, this is the only one I could remember off the top of my head, and I don't play a rogue!