The goal is to have TFS build and deploy 2+ different configurations, and have the web.config transform files include the intended content in their output. This in an ASP.NE
The Drop does not actually do any transforming. What you need is to add /p:DeployOnBuild=True
to the MSBuild Arguments.
This will create a Package that can then be used to install the website either via command line or using the IIS Import Application wizard.
If what you are after is to directly publish more than one configuration that is a whole other story and that is how I stumbled onto this post.