I already posted this on the necromancer forum, but as it is a bug, I am going to copy the important parts from it to here:
First off I’m assuming following premises are true:
1) Downed state health is directly in related to your normal health.
2) Downed state damage taken per tick is a percentage of your downed health.
Time to bring some math to the table:
https://docs.google.com/spreadsheet/ccc?key=0AmyNeYH2QDd_dEV2ZUZuRTVjUHRsWUdDNHVuNllNbXc&usp=sharing
Excuse my horrible table-editing skills.
Everything was done in lvl80 area with lvl80 character and heart of the mists.
What we can see here is whole a lot of rounding errors due to game rounding numbers. That aside, numbers in PvP are virtually same, every profession is equal in terms of downed health. In PvE however, we can notice a huge anomaly. Necromancer’s Health/Tick ratio roughly 40,0 while other professions have roughly 13,3. This is important to get every profession on same footing as test professions had different amounts of maximum health.
Conclusion: Necro takes 1/3 of the tick at same maximum health as the other professions. As things work with percentages, it means that there is 2 possiblities, one of which is highly unlikely.
1)Necro has 1/3 of the downed health compared to other professions.
2)Necro takes 1/3 per tick compared to downed health compared to other professions.
And here we disprove that: I made my self down, counted the ticks it took me to die from first down. I died on 31th tick. The elementalist did the same and counted 31 also. With the higher ticks. Which means the elementalist lost more health—>elementalist has more downed health.
Final conclusion: Necromancer in PvE has 1/3 of the downed health compared to every other profession in the game. This issue does not exist in PvP.
I think I should remove this quote given the recent developement.