Until we reach 60 the Mana Pool is all over the place too - the amounts arent proper to the amount spells cost - you often miss 10-20 more mp to cast Blizz 3 because you werent at max when you started, then at other times you get an auto tick and could cast one more AoE instead of flare and waste the whole chain.

Lvling is always a mess, when were at 60 we finally can get used to a new rotation and to mp values to get it right all the time =.=