The only problem I have with the Cowboys now is that they don't get started until the second half. But to make one of the best defenses in the NFL look so bad in the second half, I'm not gonna complain. 
Interestingly, they only start slow against tougher defenses. In the Giants game, the Cowboys had a 17-0 lead mid-way into the second quarter.

I didn't get to watch the 'Phins game.

I look at the sluggishness of the offense as a result of facing the NFL's best defense (or, at least, one of). But, they were able to wear them down in the second half.
which is also why I like receiving the ball at the start of the second half, YOU get to set the tone. 