Irule Wildcard with excules

Try this:

when HTTP_REQUEST {
    if { [string tolower [HTTP::uri]] contains "_vti_bi" } {
      switch -glob [string tolower [HTTP::uri]] {
        "/_/_vti_bin/client.svc/ProcessQuery" {
            return
        }
        "/*/_vti_bin/sites.asmx" {
            return
        }
        default {
            HTTP::redirect "http://www.xyz.com"
        }
      }
    }
}