If you assume the impossible of never missing a med tick + c2 + continuous cantata, sunstrike is under 30 sustained DPS; 21 mana medding, 11 mana c2, 13 mana cantata... so 46 per 6 seconds, 1 sunstrike per minute basically. A non-60 wizard in a realistic setting is doing like 15 sustained DPS or lower... which is basically on par with a non-epic paladin tank, or a non-epic bard, or a level 49 enchanter animation. Not really sure how your weird math made you think you could sustain rend for 19 DPS.
Even burst DPS for wizards is... not great. I mean, ok, whatever. They can spam draught of ice for a theoretical 135+ DPS, or even more from sunstrike or Velious spells. But that's impossible in reality because you pull aggro. In an xp group you get summoned and beat on and you waste healer mana and mess up rogue backstabs and shit. In a raid you die. Even when a tank is using clickies like a mallet for aggro, wizards can't go balls to the wall spamming ANYTHING without pulling aggro within like 30 seconds.
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