Stat development of intelligence sets level 50 to level 75

[Skillless]

Introduction
The massive amount of endgame mages wearing strength sets and the recent forum threads about game and gear rebalancing made me wonder if the top intelligence set Fiery is bad per se - or "only" inferiour to level 75 strength gear.
To see how Fiery fits into the history of intelligence sets, I compared the top wand sets from level 50 to 75. I took the level 50 set (Shadow) as a base and calculated the percentage of change compared to level 50 for each set. To focus on the gear stats only I compared the sets on the same level 76 toon.

And as everything looks official as a chart:

Offense stats


Damage and DPS have been going up steadily over the levels. With the exception of the Enchanted set crit has been increased but seems to be stagnating from level 70 to 75. Hit% is on an even level, only Shadow and Fiery add to that stat.

Defense stats


For the defensive values, Sand Goddess is an exceptional set, peaking in dodge and armor. That might be one reason for the weak image of Fiery, the level 70 set spoiled the defense searching mages.
With the exception of Enchanted, mana regeneration is on an even level and interestingly health regeneration has been on a steady decline over the last 20 levels.

Heal and skill damage


In my opinion the most important category, heal and skill damage as those show the value of a mage for the group.
Skill damage has been increasing over the levels, although not linearly. Sand Goddess and especially Lilith seem to be slightly disappointing as skill damage and heal isn't increasing as much as for the other sets.
While skill damage climbs, heal doesn't improve much with the better gear. On the same toon, wearing Fiery only improves heal 11 % compared to Shadow. Heal isn't as gear dependent as the damaging skills.

Conclusion
In conclusion the development of intelligence gear from level 50 to level 75 seems to be widely steady and linear - with two major exceptions: Enchanted is a somehow odd set with it's missing crit and mana regeneration and Sand Goddess has far too much dodge and armor in comparison with it's neighbors.
So Fiery is not a bad set seen in this context - it just doesn't fit the demand of defensive focused sets now, as Sand Goddess and 75 strength sets are better fitting for that.