[mwatt]

My own memory of this varies a little from what has been stated so far. While it was true that a snared mob would at some point come to a stop while running away, the stopping point did not occur at the same point the mob began to run. As an estimate, once the mob has taken a bit more damage after it has begun it's run away mode - say half of the remaining health perhaps, then it would usually come to a stop. I actually see an effect similar to this already in place. Mobs slow down a lot more as they take more damage in their flee cycle.

Having said the above, I agree on three things that have been stated by many:
1) When mobs begin their run, their initial speed seems faster than it was on live.
2) They juke and dodge with much higher frequency than the mobs did on live.
3) The hit box on many if not most mobs seems much more narrow from behind than it did on live.

When all three of these factors are combined together, the result is that chasing down a mob and killing it when it runs is significantly harder than it was on live. God help you if your attack skills aren't maxed.