Prophet's Lesson appears to take place just after the Cataclysm as the mortals of Azeroth struggle to recover from the devastation and put an end to Deathwing. The worgen are officially Alliance and Anduin is studying with Velen, so this definitely puts it after Wolfheart in the time line, but Anduin also mentions the rift between himself and his father, which means the story likely takes place before Varian Wrynn: Blood of our Fathers. In Prophet's Lesson, Anduin is studying with Velen as well as helping the draenei take care of sudden group of guests that grows larger by the day, human refugees from the Cataclysm who seek Velen's guidance.
Velen, however, is seeing no one but Prince Anduin -- and this hasn't gone unnoticed by the draenei who are no longer allowed to seek audience with the Prophet. But Anduin has one very pointed question for Prophet Velen: Why didn't he warn the world about the Cataclysm?
Hutcheson did a masterful job with Velen's character, shedding a little light (no pun intended) on what exactly the draenei have been up to during Cataclysm. You can read the full story on Blizzard's newly revamped Expanded Universe site.