You could be right that Izzet is better because Hellspark is much more aggressive than Viscera Dragger. The loss of Strix hurts, though. Anyway, onto some comments!
What is Quickling really doing for you here? You don't want to bounce the Raptors and everything else is just too expensive so your 2/2 flier comes out too late. I'm also not sold on Niblis of the Breath, the card is just too slow. Jalira looks oddly out of place, as well.
I would definitely want three Military Intelligence and some more two-drop creatures. Goblin Shortcutter could be good to turn Brackwaters into burn spells and let you swing through Baneslayers.
-3 Quickling
-3 Niblis of the Breath
-2 Jalira
+1 Vapor Snag
+4 Goblin Shortcutter
+3 Military Intelligence
Thoughts?
Hellspark is indeed pretty awesome with Evolve.
I actually sort of like the Quicklings here. 4 mana to get a 2/2 flyer and get another activation out of hellspark elemental isn't terrible. The mana is less important with the
Brackwater Elemental as well since they don't sac until they attack/block and even then not till EoT. Meaning you can T3 Brackwater> T4 attack for 4 then cast Quickling to bounce it back into your hand and leave a 2/2 behind with 2 mana still up. With a Brackwater Elemental in hand that can still be used again 2 times (cast and attack again, then Unearth and attack again) which also leads to a potential 3 Evolve triggers. They also work well with Pestermite and at the worst allow us to make some tricky blocks if we have to.
I have found them to be relatively useful as a means of saving Raptors as well. Yeah, we prefer not to bounce them because we lose all our +1/+1 counters, but when the alternative is having it go to the GY or get exiled, the tradeoff isn't bad. Especially since the deck has plenty of means of getting a Raptor back up to being respectable and they only cost
I considered Shortcutter, and that may actually not be a bad idea here. I noticed there aren't a whole lot of good 1-2 drops creatures in red and blue outside of what we are already running, at least ones that don't require building around (like Kiln Fiend or Triton Shorestalker).
Jalira was a recent addition, mostly included because I liked the interaction with her and the Unearth creatures. Attack with Hellspark/Brackwater then sac into a another creature, then the following turn Unearth, attack, and sac into a free creature is a pretty tasty scenario. This does take quite a bit of mana to do though (5-6) and may just be a bit too slow to be worth it. The idea of sacing into Hellspark isn't appealing either.
Not sure how I feel about Niblis.
They have been helpful to push damage through with their ability, and as a generic 2 power flier they do the trick well enough. They ARE somewhat slow to tap things down, but a lot of what seems to make this deck work is the abundance of fliers. There aren't a ton of great defenses against a huge rush of fliers in the game currently.
I have noticed that removal tends to get stretched thin when an opponent has to deal with a large rush of fliers. Raptors and the Dragons have to be answered quickly or they kill you. Pestermites and Niblis pose much less of a threat, but still represent 2 points of evasion damage and also give us some utility in getting attacks through or locking creatures down. Quicklings helps serve this purpose as well, while even further helping to stretch removal thin by blanking it by bouncing our creatures.
I do like the suggestion of Military Intelligence though and I do think you may be correct about Jelira just being too slow and derpy.
-2 Jalira
-1 Niblis
+3 Military Intelligence
Gonna try this out some later tonight.