Well if you've got good BJJ, you'll be a threat on the ground. And if you've got good wrestling you can dictate where the fight takes place. Wrestling all day, err'day.
"Leg kicks don't hurt us, we don't give a FUCK about leg kicks, we're WRESTLERS!" - Kevin Randleman wrasslin' > everything
Imagine if Sonnen had real jitz skillz to go along with his wrestling. Wrestling is the so far ahead of bjj it isn't funny.
There is a far greater focus on control in wrestling, which is why wrestlers with good submission defense often destroy top notch BJJ players in MMA matches. In a grappling tournament where a fight must end in submission, wrestling doesn't usually prevail.
Or at least master Sub Defense if you are relying on the Wrestling. It appears that a variety of skills are now necessary to compete at the top.
A wrestler that knows nothing of BJJ will get tapped like a little girl in seconds. A wrestler that has a solid understanding of, and training in BJJ defense will lay on a pure BJJer for a decision fairly easily.