Math confusion - +20 int but -2235 mana

[Iralien]

So I picked up a new set of pants today. They had a nice chunk of Haste instead of Mastery and a Red instead of Yellow socket, so I took them, gemmed them, and added a spell thread.

Old pants [http://www.wowhead.com/item=63464]
New pants [http://www.wowhead.com/item=58107]

The 3 core stats are a wash, so the ONLY differences are the Gems, socket bonuses, and combat ratings.
New gems = 60 intellect, 20 spirit
Old gems = 40 intellect, 20 spirit, 20 haste.
Ratings (discounting reforging) is a swap from Mastery to Haste.

So can someone explain why I lose 2,235 mana when equipping the new pants? There must be something obvious to explain this...

SS or it didn't happen:

http://img687.imageshack.us/i/wowscr...0711135021.jpg
http://img684.imageshack.us/i/wowscr...0711135043.jpg

[Littlebruddy]

did you have kings up when you were looking at one? are you using a gear-swapping mod/bliz ui that is also equipping a different piece of gear? how is your intellect affected?

[Shornaal]

Check if your metagem is still active.

[Iralien]

Check if your metagem is still active.

Cough. Cough. Shuffle. Shuffle.

Yeah, ok. Nevermind then.

[Manito]

Check if your metagem is still active.

^ check your meta gem.