Hearthpwn

Mana curve should be one of your secondary considerations if there is not an obvious front runner among the cards.  So if you get Chillwind Yeti, Bloodfen Raptor and Corehound it is pretty obvious you should take Chillwind Yeti.

However if you get Bloodfen Raptor, Dragonling Mechanic, and Ironfur Grizzly your decision tree should take mana curve into account.  

Light on 2 drops?  Take the Raptor.

 Light on 4 drops or have some cards that can benefit from additional minions (Frostwolf Warlord, Sea Giant, etc) pick the Mechanic.

 If you are late in your draft and don't have any 1 or 3 drops then maybe take the Grizzly.  3 drops are generally not as important because a lot of 2 drops kill 3 drops and a lot of 3 drops can't kill 4 drops.  The few value exceptions are cards like Harvest Golem.  So I tend to devalue the need for 3 drops (2 and 4 are much more important).

Quote from Lenor »

Quote from TheRealHollywood »

"The mana curve is irrelevant most of the time"

 Worst. Statement. Ever.

Went 7+ multiple times while having mostly 4 mana cost minions.

If you pick bloodfen raptor over a chillwind yeti just because you don't have enough 2 cost minions you're gonna have a bad time.

I stand by my statement.

Congratulations on your achievements. 7 arena wins is good but if you want to start consistently hitting 10+ wins then you have to understand that your mana curve dictates tempo, and is one of, if not the most important aspects of this game.

Try looking up some strategy articles about the importance of the resource curve from the WoWtcg, which is the game that the majority of the mechanics and the entire combat system of HS is based off of (albeit in a slightly dumbed-down form due to not having any true instant cards).