I'm not a pro or anything (I'm actually relatively new to WoW), and this isn't meant to be accusing, but the above post doesn't seem to be too mana efficient. At level 20, your Arcane Missiles will do about 144-148 damage and cost 140 mana. Thats about 1.05 (I'm a nerd) damage per mana point. Rank 4 Frostbolt does an average of 78 damage and costs 63 mana with the Elemental Precision talent. That means Frostbolt does about 1.23 damage per mana point. Although Arcane Missiles is faster damage, you have to remember that if you're spamming Frostbolt with the Frostbite talent, you'll have about a 15% chance to freeze the target on each hit, allowing more time for casting and less time for the enemy to hit you.
Also, at level 20 Arcane Explosion is not mana efficient at all, dealing an average of 60 damage and costing 75 mana. I'll stop bothering you with damage/mana, but its obvious that this spell is not efficient on a 1v1 basis (which I believe is what the above poster was talking about, but I may be wrong).
Like I said, I'm no pro, but here's my tactic for 1v1 (which is probably flawed in its own way):
Frostbolt until the enemy is too close for you to cast without being hit.
For less DPM but higher DPS, use Fireblast
Use Frost Nova and run until you are just within range of Frostbolt.
Rinse and Repeat.
Also, at level 20 Arcane Explosion is not mana efficient at all, dealing an average of 60 damage and costing 75 mana. I'll stop bothering you with damage/mana, but its obvious that this spell is not efficient on a 1v1 basis (which I believe is what the above poster was talking about, but I may be wrong).
Like I said, I'm no pro, but here's my tactic for 1v1 (which is probably flawed in its own way):
Frostbolt until the enemy is too close for you to cast without being hit.
For less DPM but higher DPS, use Fireblast
Use Frost Nova and run until you are just within range of Frostbolt.
Rinse and Repeat.