Hi Joe, I tried using the Tier Subpaths measure but I would always get the total execution time for the entire PurePath. This makes sense based on the following measure description: "Represents the total execution time of subpaths started in the specified Tier."
What about creating a chart and putting the WS time measure and the Backend Time measure. Then use a Stacked Chart type so you can visualize the difference and see that the WS tier is taking most of the time. I've created one as I suggest. See below.