very few excellant clinchers dominate in the clinch, it's basically a big scramble. Out of 50 or so fights I've had, win or lose, only one ever ended by strikes inside the clinch.
But really, look at Hendo, Couture, Lindland, Karo, Aoki, Anderson (who only really dominated 2 fights with the thai clinch ever), those guys don't finish you from a clinch, they control and grind you down (exception of the thai clinch, which damages but has shitty control for the most part). And look at how much damage and time was spent in the clinch during Frye Takayama before Takayama actually got knocked out.