My bad, think I'm mixed it up with one of the early MoP beta builds.
They were experimenting with an Enrage that procs on special attack crits only, and for that purpose completely removed Overpower's crit chance for a while, and buffed it's weapon damage to be just below Mortal Strike. It felt really awkward not seeing your Overpower crit (people were in questing greens with less than 10% crit chance).
Was in response to OPs suggestion of removing the bonus crit from OP to allow better scaling with crit chance, which in itself is a fairly good point. The extra crit chance from Recklesness is wasted on Overpower, and Slam is a very expensive ability to replace all Overpowers with during Reck. Would be kind of nice if Overpower got the Chaos Bolt treatment in which all crit past 100% was turned into extra % dmg done.