Let's get this out of the way real quick: power rankings do not matter. Very simply, they are just one person's—or group of peoples'—thoughts on what teams are better than others in a very general sense, allowing them to even ignore results on the field or position in the standings. It's like college football rankings.
That said, the people who do the MLSsoccer.com power rankings right now think that the Houston Dynamo are much better than they did two weeks ago, and that's nice of them. The Dynamo entered the year ranked at No. 19, despite winning the prestigious Desert Diamond Cup in preseason.