Mages have got a miss factor programmed on. Shayd is a good example as she has a high miss rate. Anyone (including me) who had slapped a 100+ hit rate rune noticed that it didn't effect how often she still missed. Apparently Shayd because of her stun ability has a 1 in 3 chance of missing, something Dawnseeker has also confirmed. Misses are peculiar to mages and don't affect physical heroes.

However, a Mage attack can still be dodged. Hence why hit rate runes work for mages. Don't see it much PvP but its there when you attack bosses. To distinguish the two is easy, a miss will show as a miss and dodge will show as one.

Hopefully that's clearer, or more likely as clear as ditch water.