First of all, I like that you've found some flexibility for the resource metrics. 8 )
Secondly, apart from some high level capacity planning trends, I would not recommend putting a lot of focus on resource metrics within that tab. I like to think of that view as my available library and a way to get accustomed to what I have in my arsenal.
Now, how I use my arsenal is by looking at the wait analysis first and then bringing into view the necessary resource metrics beneath the wait trend view(s).
Set your context on the trend view (can do custom interval as well as the pre-defined ones) -> click on the resource tab below the trend graph -> add appropriate resource charts that the waits tell you to focus on.
All is within that context and auto-correlated with the same time frame.
That, sir, is a very workable solution and is doing the job quite nicely thus far. Thank you for your help!