In 14w02a and the following bug fix versions, I've observed some buggy Endermen behavior that is likely caused by the way teleporting was changed. (That's what I assume. It may be caused by something different)

1. Endermen take a very long time to teleport out of water, rain or lava. There is a huge delay between when they touch a liquid and when they actually teleport, rather than instantaneously. Sometimes when this occurs, the enderman will appear to try and teleport (fly across the screen), but will still be in the water.

2. Another huge delay in teleportation occurs when they stand in day light

3. They rarely teleport in attempt to dodge melee attacks. I've been able to kill an Endermen from full health with a wooden sword while aiming at their chest without a single teleportation.

In general Endermen teleportation seems to be a lot slower

I apologize if this is a dupe, I could not break down the search results.