Blizzard clearly designed the fights, even hard modes, around giving 10mans leeway when it came to DPS. For example, on Ultraxion Heroic 10man you needed something like 34k dps to beat enrage. On 25m heroic you needed 41k.
This is represented in WOL parses. The 25man parses are always higher. They assume that you are missing raid buffs. This helps. A raid in 378 gear could possibly do heroic morchok from a dps standpoint if you had a great raid group with full buff/debuff coverage. If you were missing critical buffs (5% crit, 8% spell damage taken, 10% spell damage), it would be hard if not impossible. That's only for DPS. If you have undergeared healers, I dont think its possible to do heroic morchok, although the 10% nerf certainly helped.