Has the problem with WHM in raids fixed in SB?

[xNewbx]

Not sure where you're reading this, but highest parse for WHM is less than 100 from SCHs top parse, and 200 above SCH in Lakshmi. This is not considering Balance uptime.
Of course, SCH also brings utility to the raid that can easily make up that difference.

So not sure where you're getting this huge gap in DPS power from. Heck, Monk was around this much stronger to DRG in 3.0, and guess what happened to them?

But here I thought the AST putting the balance on one person throughout a fight was supposed to represent the average dps that class could do?...

The issue with the SCH keeping up in DPS is the fact they offer the damage utility, whereas the WHM does not. And that extra crit buff feels amazing. Honestly if the WHM did a bit more damage, I think it'd be a very good balance between the healers.

WHM offering high, consistent damage.
SCH slightly lower, but a great crit buff.
AST the lowest personal DPS but has a chance to offer the most damage utility.

I personally think an RNG class should offer more if the cards play in their favor. As long as it's not extremely far over. Because, it's rng.