Looking at the 0/0/49 +12 build on manoutoftime:
689.21 Frostbolt w/Waterbolt + IV Avg'd
Looking at the 10/47/3 +1 build on manoutoftime(51 points in fire is unnecessary, and you really need 3 in elemental precision):
672.80 Fireball x8 / Scorch x1 w/MF avg'd
This is actually something I expected. You see, deep fire really needs more gear to pull ahead. It scales better, but you don't currently have the gear to support it.
Warcrafter isn't working for me at the moment(my work comp doesn't like it, I think). However, are you making sure Imp Scorch is factored in?
Finally, I have to assume this is something you're doing for raids? Because if not, manoutoftime at least may not be the strongest tool for you, as raid conditions don't always apply to 5 mans, and certainly not to raids.
Here's my personal advice(I'm assuming you're a raider, tell me if that's not the case as my advice won't exactly apply):
Try out either a 40/21/0 or a 40/0/21(I'd actually suggest the latter unless you can pick up some serious hit rating soon, more on that later). The reason is that both of those builds give you a leg up when you're not quite epicced out.
Now, why would I suggest the Arcane/Frost, you may ask? As you may or may not know, +hit is the strongest raid stat in the game for mages until it's capped out. As I've mentioned, yours is low. Now, what you probably don't know is that a while back, a bunch of theorycrafters spending a lot of time parsing data discovered a peculiar behavior. What these theorycrafters found is that frost seemed to have a higher hit chance than fire, and they set out to discover why. It took time, but eventually, they discovered the cause.
Something else you may not know is that the previous incarnation of elemental precision was a 6% +hit, not a 3% with the 3% mana cost reduction. Blizzard changed it a while back, but it seems they made an error in coding.
It still gives frost the full 6%.
This is known as the "Precision Ghost Hit". It's huge for entry level raiding. And I mean HUGE. It's basically a 38 hit rating bonus to frosties. And that just can't be ignored.
Try plugging the information into Warcrafter based on those builds and see what you get. You may just like the results.