As it stands, the 5 parameters (metrics 1, 2 and 3, same scale and time span) have default values and any other combination requires clicking and scrolling through the page with a sizeable list of metrics. This means switching from one aspect of quality to another is difficult and impractical.
Ideally, I would like to save a configuration into a list of saved configurations and click a configuration from the list to immediately see the appropriate chart. However, I understand that might take a bit of time, so there is a workaround which will also get the job done and should be much, much easier to implement. If a specific parameter configuration was included into the URL as HTTP GET parameters, the view would become bookmarkable, in essence delegating view management to the browser. It is not as elegant, but is quite flexible and gets the job done.
I would be surprised if it turned out to be more than several hours of work: it might be much less, though.