Does that mean the colorado defense is great? It was only a 10 yard difference, but with the limited data we have up until this point it's all we can compare. So far the data doesn't prove that utah's secondary is good. Could they be? Sure. But there's no evidence of that yet, in part because they haven't played a good passing team to test them.
What should really scare utah is that they are facing the best passing quarterback in the pac-12 and one of the best defenses in the country in the turnover margin.